8 “By” Idioms: Meanings, Examples & Grammar Guide

1. Introduction to Idioms with “By”

Idioms are an essential part of fluent English. They are used everywhere—at work, school, social events, and in media. Learning idioms will make your English sound more natural and help you understand native speakers better.

In this lesson, you will learn eight common idioms that start with the word “by.” Each idiom has a clear meaning and is used in everyday speech and writing.

The Eight Idioms

#	Idiom	Meaning
1	by heart	from memory
2	by hand	not by machine; manually
3	by chance / by coincidence	accidentally; without planning
4	by mistake / by accident	not on purpose; unintentionally
5	by the book	strictly following rules
6	by and large	generally; on the whole
7	by leaps and bounds	very quickly; tremendously
8	by word of mouth	through people talking, not advertising

Why Learn These Idioms?

• They are extremely common in both spoken and written English.
• They express ideas concisely and naturally.
• They help you sound more fluent and sophisticated.
• They appear in exams like IELTS, TOEFL, and GRE (especially in listening and reading).

Word Meaning Section

Word / Phrase	English Meaning	Bengali Meaning
Idiom	a phrase with a non-literal meaning	বাগধারা
Memory	ability to remember	স্মৃতি
Accident	something unplanned	দুর্ঘটনা
Coincidence	chance occurrence	কাকতালীয় ঘটনা
Rule	a prescribed guide	নিয়ম
Whole	complete	সম্পূর্ণ
Leap	a big jump	লাফ
Mouth	opening for speaking	মুখ
Advertising	promoting products	বিজ্ঞাপন
Marketing	promoting and selling	বিপণন

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2. By Heart

Meaning

By heart means to know something completely from memory, without needing to look at it.

8 Examples with Explanations

#	Example	Explanation
1	She knows the poem by heart.	She has memorized it completely.
2	I learned my multiplication tables by heart.	I can recite them without thinking.
3	He knows all the lyrics by heart.	He can sing every word from memory.
4	The actor knew his lines by heart.	He didn’t need the script.
5	Please learn this list by heart for the test.	Memorize it fully.
6	My grandmother knows many prayers by heart.	She remembers them without reading.
7	Children often learn nursery rhymes by heart.	They memorize them easily.
8	I know your phone number by heart.	I have memorized it.
9	She recited the speech by heart.	She did not use notes.
10	Do you know any songs by heart?	Can you sing from memory?

Word Meaning Section

Word / Phrase	English Meaning	Bengali Meaning
By heart	from memory	স্মৃতি থেকে
Memorize	to learn completely	মুখস্থ করা
Recite	to say aloud from memory	আবৃত্তি করা
Lyrics	words of a song	গানের কথা
Script	written dialogue	চিত্রনাট্য
Multiplication table	table of products	গুণের নামতা
Nursery rhyme	simple poem for children	ছড়া
Prayer	words addressed to a deity	প্রার্থনা

Related Phrasal Verb

Phrasal Verb	Meaning	Example
Learn by heart	memorize	I need to learn this speech by heart.
Know by heart	have memorized	She knows the rules by heart.
Reel off	recite quickly	He reeled off the dates by heart.

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3. By Hand

Meaning

By hand means done manually, using the hands, not by machine.

8 Examples with Explanations

#	Example	Explanation
1	She made this sweater by hand.	She knitted it herself, not a machine.
2	The artist painted the portrait by hand.	Not printed.
3	These shoes were made by hand.	Handcrafted.
4	He wrote the letter by hand.	Not typed or printed.
5	The carpet was woven by hand.	Manual weaving.
6	They embroidered the design by hand.	Done with needle and thread.
7	I prefer bread made by hand.	Artisan bread.
8	The wooden toy was carved by hand.	Hand-carved.
9	The card was written by hand.	Not printed.
10	She sewed the dress by hand.	Stitched manually.

Word Meaning Section

Word / Phrase	English Meaning	Bengali Meaning
By hand	manually; not by machine	হাতে; হস্তচালিত
Handcrafted	made by hand	হস্তনির্মিত
Embroider	decorate with needlework	সূচিকর্ম করা
Weave	make cloth	বুনন করা
Carve	cut into shape	খোদাই করা
Artisan	skilled craftsperson	কারিগর
Sew	stitch	সেলাই করা
Knit	make fabric with yarn	বোনা

Related Phrasal Verb

Phrasal Verb	Meaning	Example
Make by hand	produce manually	She made the jewelry by hand.
Write by hand	write with pen, not type	He wrote the note by hand.
Draw by hand	draw without digital tools	The sketch was drawn by hand.

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4. By Chance / By Coincidence

Meaning

By chance or by coincidence means accidentally, without planning.

8 Examples with Explanations

#	Example	Explanation
1	I met my old friend by chance at the mall.	Unplanned meeting.
2	By coincidence, we were both wearing red shirts.	Unplanned similarity.
3	She found the book by chance in a used bookstore.	Unexpectedly.
4	He discovered the restaurant by chance.	Came across it without looking.
5	By a strange coincidence, we were born on the same day.	Unlikely similarity.
6	I heard about the job by chance.	Accidentally learned.
7	We sat next to each other by chance on the plane.	Not arranged.
8	They met by chance at the conference.	Unexpected encounter.
9	By sheer coincidence, they had the same name.	Purely accidental.
10	I found my lost keys by chance.	Accidentally found.

Word Meaning Section

Word / Phrase	English Meaning	Bengali Meaning
By chance	accidentally	দৈবক্রমে
Coincidence	chance occurrence	কাকতালীয়
Accidentally	by accident	হঠাৎ করে
Unplanned	not planned	অপরিকল্পিত
Encounter	meeting	সাক্ষাৎ
Sheer	complete; pure	সম্পূর্ণ
Strange	unusual	অদ্ভুত
Used bookstore	shop for second-hand books	পুরনো বইয়ের দোকান

Related Phrasal Verb

Phrasal Verb	Meaning	Example
Come across	find by chance	I came across an old photo by chance.
Run into	meet by chance	I ran into my professor by coincidence.
Bump into	meet unexpectedly	She bumped into a friend at the airport.

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5. By Mistake / By Accident

Meaning

By mistake or by accident means unintentionally; not on purpose.

8 Examples with Explanations

#	Example	Explanation
1	I called the wrong number by mistake.	Not intentional.
2	She took my umbrella by accident.	Thought it was hers.
3	He deleted the file by mistake.	Did not mean to.
4	I spilled the coffee by accident.	Not on purpose.
5	They sent the email to the wrong person by mistake.	Error.
6	The baby knocked over the glass by accident.	Not intentional.
7	I forgot to attach the document by mistake.	Oversight.
8	She left her phone at home by accident.	Unintentional.
9	I paid the bill twice by mistake.	Error.
10	He stepped on my foot by accident.	Unplanned.

Word Meaning Section

Word / Phrase	English Meaning	Bengali Meaning
By mistake	unintentionally	ভুলবশত
By accident	not on purpose	অনিচ্ছাকৃতভাবে
Intentionally	on purpose	ইচ্ছাকৃতভাবে
Unintentionally	not deliberately	অনিচ্ছাকৃতভাবে
Oversight	careless mistake	ত্রুটি
Spill	cause liquid to fall	ফেলা
Delete	remove	মুছে ফেলা
Attach	add a file	সংযুক্ত করা
Step on	tread on	পা দেওয়া

Related Phrasal Verb

Phrasal Verb	Meaning	Example
Dial wrong	call an incorrect number	I dialed wrong by accident.
Mix up	confuse	I mixed up the names by mistake.
Slip up	make a careless error	He slipped up and sent the wrong file.

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6. By the Book

Meaning

By the book means strictly following the rules, regulations, or standard procedures.

8 Examples with Explanations

#	Example	Explanation
1	The auditor does everything by the book.	Follows rules exactly.
2	She is a manager who goes by the book.	Adheres strictly to policy.
3	The referee followed the rulebook by the book.	No exceptions.
4	He handled the case by the book.	Legally and correctly.
5	They ran the inspection by the book.	Thorough and compliant.
6	The teacher grades by the book.	Uses the rubric strictly.
7	My father insists on doing taxes by the book.	No shortcuts.
8	The police acted by the book.	Followed procedure.
9	She is too rigid; always by the book.	Not flexible.
10	The project was completed by the book.	According to plan.

Word Meaning Section

Word / Phrase	English Meaning	Bengali Meaning
By the book	strictly following rules	নিয়ম মেনে
Auditor	person who checks accounts	নিরীক্ষক
Policy	official rule	নীতি
Rubric	scoring guide	মূল্যায়ন নির্দেশিকা
Referee	official in a sport	রেফারি
Inspection	careful examination	পরিদর্শন
Compliant	following rules	নিয়ম মেনে চলা
Flexible	able to change	নমনীয়
Shortcut	easier but improper way	শর্টকাট

Related Phrasal Verb

Phrasal Verb	Meaning	Example
Go by the book	strictly follow rules	She goes by the book in every decision.
Stick to the rules	obey rules	He sticks to the rules by the book.
Play by the book	act according to rules	The company plays by the book.

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7. By and Large

Meaning

By and large means generally, on the whole, or for the most part.

8 Examples with Explanations

#	Example	Explanation
1	By and large, the project was a success.	Overall positive.
2	By and large, people are kind.	Generally true.
3	The weather, by and large, has been mild.	Mostly.
4	By and large, I enjoy my work.	Overall.
5	By and large, the new policy is beneficial.	On the whole.
6	The students, by and large, did well on the test.	Generally.
7	By and large, the economy is improving.	Generally.
8	Her performance was, by and large, excellent.	Mostly excellent.
9	By and large, the conference was informative.	Overall.
10	By and large, I agree with you.	Generally agree.

Word Meaning Section

Word / Phrase	English Meaning	Bengali Meaning
By and large	generally speaking	মোটামুটি; সাধারণভাবে
Overall	considering everything	সার্বিকভাবে
On the whole	generally	মোটের উপর
For the most part	mostly	অধিকাংশ ক্ষেত্রে
Beneficial	helpful	উপকারী
Mild	not severe	মৃদু
Informative	providing information	তথ্যবহুল
Economy	financial system	অর্থনীতি

Related Phrasal Verb

Phrasal Verb	Meaning	Example
By and large, come out	to result in general	By and large, the plan came out well.
By and large, turn out	to end up	The event turned out well by and large.
By and large, work out	to succeed generally	Things worked out by and large.

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8. By Leaps and Bounds

Meaning

By leaps and bounds means very quickly, tremendously, or by a large amount.

8 Examples with Explanations

#	Example	Explanation
1	Her English improved by leaps and bounds.	Great improvement.
2	The company grew by leaps and bounds.	Rapid growth.
3	Technology has advanced by leaps and bounds.	Huge progress.
4	The child’s reading skills progressed by leaps and bounds.	Fast improvement.
5	Sales increased by leaps and bounds last year.	Tremendous increase.
6	His confidence grew by leaps and bounds.	Much more confident.
7	The city expanded by leaps and bounds.	Rapid expansion.
8	Her career took off by leaps and bounds.	Quick success.
9	The software improved by leaps and bounds.	Major updates.
10	My understanding of grammar increased by leaps and bounds.	Massive learning.

Word Meaning Section

Word / Phrase	English Meaning	Bengali Meaning
By leaps and bounds	very quickly; greatly	দ্রুত; ব্যাপকভাবে
Improve	to get better	উন্নতি করা
Grow	to increase	বৃদ্ধি পাওয়া
Advance	to move forward	অগ্রসর হওয়া
Progress	to develop	উন্নতি করা
Expand	to become larger	প্রসারিত হওয়া
Take off	to become successful quickly	দ্রুত সাফল্য পাওয়া
Confidence	belief in oneself	আত্মবিশ্বাস

Related Phrasal Verb

Phrasal Verb	Meaning	Example
Shoot up	increase very quickly	Prices shot up by leaps and bounds.
Take off	succeed rapidly	The business took off by leaps and bounds.
Grow by leaps and bounds	grow very fast	Her vocabulary grew by leaps and bounds.

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9. By Word of Mouth

Meaning

By word of mouth means through people talking to each other, not through advertising or official announcements.

8 Examples with Explanations

#	Example	Explanation
1	The restaurant became popular by word of mouth.	People recommended it.
2	We heard about the sale by word of mouth.	Through a friend.
3	The news spread by word of mouth.	Person to person.
4	The book became a bestseller by word of mouth.	People told others.
5	They found the apartment by word of mouth.	Through a neighbor.
6	The campaign relied on word of mouth.	No advertising.
7	By word of mouth, everyone knew about the event.	Informal spreading.
8	The band gained fans by word of mouth.	Through live shows.
9	The app grew by word of mouth.	Users recommended it.
10	We learned about the job opening by word of mouth.	Through a colleague.

Word Meaning Section

Word / Phrase	English Meaning	Bengali Meaning
By word of mouth	through people talking	মুখে মুখে প্রচার
Popular	liked by many	জনপ্রিয়
Bestseller	a very popular book	বেস্টসেলার
Campaign	organized effort	প্রচারণা
Rely on	depend on	নির্ভর করা
Recommend	to suggest	সুপারিশ করা
Spread	to circulate	ছড়িয়ে পড়া
Colleague	coworker	সহকর্মী

Related Phrasal Verb

Phrasal Verb	Meaning	Example
Pass on	to communicate	They passed on the news by word of mouth.
Tell around	to spread by talking	The rumor was told around by word of mouth.
Get around	to circulate	Word got around about the sale.

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10. Grammar Focus: Prepositional Idioms and Their Patterns

These idioms all begin with the preposition “by.” They function as prepositional phrases and often act as adverbs or adverbial phrases in a sentence.

Structure

by + noun / determiner + noun

Idiom	Structure
by heart	by + heart (noun)
by hand	by + hand (noun)
by chance	by + chance (noun)
by coincidence	by + coincidence (noun)
by mistake	by + mistake (noun)
by accident	by + accident (noun)
by the book	by + the + book (noun phrase)
by and large	fixed phrase
by leaps and bounds	fixed phrase
by word of mouth	fixed phrase

Usage in Sentences

These idioms often answer how something happened.

Question	Answer
How did you learn it?	By heart.
How was it made?	By hand.
How did you meet?	By chance / by coincidence.
How did you call the wrong number?	By mistake / by accident.
How does she follow the rules?	By the book.
How is the weather generally?	By and large, it’s mild.
How fast did you improve?	By leaps and bounds.
How did you hear about it?	By word of mouth.

Affirmative, Negative, and Interrogative Forms

These idioms usually appear in statements, but can be used in questions and negatives.

Form	Example
Affirmative	I learned it by heart.
Negative	I didn’t learn it by heart.
Interrogative	Did you learn it by heart?
Affirmative	She made it by hand.
Negative	It wasn’t made by machine.
Interrogative	Was it made by hand?
Affirmative	By and large, it was good.
Negative	By and large, it wasn’t bad.
Interrogative	By and large, was it good?

5 WH-Question Examples with Answers

#	WH Question	Possible Answer
1	How do you know the poem?	I know it by heart.
2	Why did you call the wrong number?	I dialed it by mistake.
3	How did the business grow?	It grew by word of mouth.
4	When did you meet your friend?	By chance, at the mall.
5	How did you improve so fast?	By leaps and bounds, through daily practice.

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11. Special Tips for Learners

Tip 1: Learn Idioms in Context

Don’t memorize isolated words. Learn the full idiom and an example sentence.

Tip 2: Group Synonyms Together

Notice that by chance = by coincidence and by mistake = by accident. Learning them as pairs helps memory.

Tip 3: Practice with Personal Examples

Ask yourself:

• What do I know by heart?
• Have I ever made something by hand?
• Did I ever meet someone by chance?
• Did I ever call the wrong number by mistake?
• Do I know someone who goes by the book?
• By and large, am I happy?
• What can I do to improve by leaps and bounds?
• How did I hear about my favorite app? By word of mouth?

Tip 4: Listen for These Idioms

Watch TV shows, movies, and interviews. Notice how native speakers use these phrases.

Tip 5: Use Idioms in Speaking and Writing

Try to insert one idiom into a conversation or email this week.

Tip 6: Create Flashcards

Front: idiom. Back: meaning + one example sentence.

Tip 7: Don’t Translate Word-for-Word

Idioms have non-literal meanings. Learn them as chunks.

Tip 8: Review Regularly

Spaced repetition helps retention.

Tip 9: Use Online Resources

Download vocabulary lists and practice quizzes.

Tip 10: Teach Someone

Explaining idioms to someone else reinforces your own understanding.

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12. Tips for Competitive Exams: IELTS, TOEFL, GRE

IELTS

Skill	How Idioms Help	Strategy
Speaking Part 2	Describing a person or event	Use “by heart,” “by hand,” “by chance” naturally.
Listening	Conversations may include idioms	Recognize them in context.
Reading	Articles and stories with idioms	Infer meaning from context.
Writing Task 2	Use idioms sparingly	Prefer “by and large” to summarize.

TOEFL

Skill	How Idioms Help	Strategy
Listening	Lectures and campus talk	Identify idioms in speech.
Speaking	Integrated tasks	Use “by leaps and bounds” to describe improvement.
Writing	Independent essay	“By and large” introduces a general point.

GRE

Skill	How Idioms Help	Strategy
Analytical Writing	Formal essays	Use “by and large” or “by the book” carefully.
Text Completion	Idioms may appear in passages	Know meanings.

Exam Rules

• Use idioms naturally; do not force them.
• In formal writing, choose neutral idioms like “by and large.”
• In speaking, idioms boost lexical resource if used correctly.
• Avoid overusing idioms; one or two per response is enough.
• Practice listening for idioms in fast speech.

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13. Practice Exercises

Exercise 1: Fill in the Blanks

Complete each sentence with the correct idiom from the list.

List: by heart, by hand, by chance, by coincidence, by mistake, by the book, by and large, by leaps and bounds, by word of mouth

1. I know your phone number ______.
2. She made this scarf ______.
3. We met ______ at the airport.
4. I sent the email to the wrong person ______.
5. He always follows the rules ______.
6. ______, the project was a success.
7. Her English improved ______.
8. The news spread ______.
9. They wore the same shirt ______.
10. I deleted the file ______.

Exercise 2: Multiple Choice Questions

Choose the best idiom for each situation.

1. Something happened without planning.
   a) by heart
   b) by chance
   c) by the book
   d) by hand
2. Something is made manually, not by machine.
   a) by mistake
   b) by heart
   c) by hand
   d) by word of mouth
3. You know something from memory.
   a) by heart
   b) by accident
   c) by and large
   d) by leaps and bounds
4. You did something unintentionally.
   a) by chance
   b) by mistake
   c) by the book
   d) by hand
5. Someone follows rules strictly.
   a) by word of mouth
   b) by and large
   c) by the book
   d) by heart
6. Something improved tremendously.
   a) by leaps and bounds
   b) by coincidence
   c) by accident
   d) by hand
7. Information spread through people talking.
   a) by the book
   b) by hand
   c) by word of mouth
   d) by and large
8. Generally speaking.
   a) by chance
   b) by heart
   c) by and large
   d) by mistake
9. Two people met without planning.
   a) by accident
   b) by heart
   c) by the book
   d) by hand
10. “By coincidence” is similar to:
    a) by chance
    b) by mistake
    c) by the book
    d) by hand

Exercise 3: Sentence Transformation / Error Correction

Rewrite each sentence using the correct idiom.

1. I know the song with my heart. → Use “by heart”
2. She made the dress by machine. → Change to “by hand”
3. We met on purpose. → Change to “by chance”
4. He called the wrong number on purpose. → Change to “by mistake”
5. She follows the rules loosely. → Change to “by the book”
6. On the whole, it was fine. → Use “by and large”
7. The company grew slowly. → Change to “by leaps and bounds”
8. I heard about the job through advertising. → Change to “by word of mouth”

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14. Answer Key with Explanations

Exercise 1 Answers

1. by heart
   Explanation: Know from memory.
2. by hand
   Explanation: Made manually.
3. by chance
   Explanation: Unplanned meeting.
4. by mistake
   Explanation: Unintentionally.
5. by the book
   Explanation: Strictly following rules.
6. By and large
   Explanation: Generally.
7. by leaps and bounds
   Explanation: Great improvement.
8. by word of mouth
   Explanation: Through people talking.
9. by coincidence
   Explanation: Unplanned similarity.
10. by accident
    Explanation: Unintentionally.

Exercise 2 Answers

1. b) by chance
   Explanation: Unplanned.
2. c) by hand
   Explanation: Manual.
3. a) by heart
   Explanation: From memory.
4. b) by mistake
   Explanation: Unintentional.
5. c) by the book
   Explanation: Strict rules.
6. a) by leaps and bounds
   Explanation: Tremendous.
7. c) by word of mouth
   Explanation: People talking.
8. c) by and large
   Explanation: Generally.
9. a) by accident
   Explanation: Unplanned. (also by chance/coincidence)
10. a) by chance
    Explanation: Synonym.

Exercise 3 Answers

1. I know the song by heart.
   Explanation: Correct idiom.
2. She made the dress by hand.
   Explanation: Not machine.
3. We met by chance.
   Explanation: Unplanned.
4. He called the wrong number by mistake.
   Explanation: Unintentional.
5. She follows the rules by the book.
   Explanation: Strictly.
6. By and large, it was fine.
   Explanation: Generally.
7. The company grew by leaps and bounds.
   Explanation: Rapidly.
8. I heard about the job by word of mouth.
   Explanation: Through people.

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15. Conclusion

Idioms beginning with “by” are common, useful, and relatively easy to learn. They add color and precision to your English, whether you are speaking or writing.

Key points to remember:

• By heart = from memory
• By hand = manually
• By chance / by coincidence = accidentally
• By mistake / by accident = unintentionally
• By the book = strictly following rules
• By and large = generally
• By leaps and bounds = tremendously
• By word of mouth = through people talking

Use these idioms in your daily conversations and writing. Listen for them in English media, and practice with the exercises above. With regular use, they will become a natural part of your vocabulary.

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Call to Action: Choose three idioms from this lesson and write one sentence for each about your own life. Then, use at least one idiom in a conversation or email this week. Record yourself saying the sentences to check pronunciation and fluency. Finally, create your own quiz with the idioms and test a friend. Keep practicing, and your English will improve by leaps and bounds!