swear

swear — verb

1. to use offensive or rude words, especially when you are angry or want to express

1.verbintransitiveB1
Definition

to use offensive or rude words, especially when you are angry or want to express strong feelings

Example

Ryo swore loudly after he hit his thumb with a hammer.

swear + adverb of manner

The driver in front cut her off, so Élise swore and sounded the horn.

Common collocations
  • swear loudly
  • swear under one's breath
  • swear at someone
  • start swearing
Synonyms
  • curse

    more formal or literary; less common in everyday speech

  • cuss

    informal, mainly American English

  • use bad language

    a polite way to refer to the action without repeating the words

Grammar Patterns

swear

swear at [someone/something]

Usage Note

Intransitive only — you cannot 'swear someone' in this sense. Use 'swear at someone' to name the target of the bad language.

Common Mistakes

He swore me when I broke his phone.
He swore at me when I broke his phone.
'swear' is intransitive in this sense; you need 'at' before the person.

2. to promise something in a very serious way, so that the person hearing you can b

2.verbtransitive / intransitiveB1
Definition

to promise something in a very serious way, so that the person hearing you can be sure you mean it, or to make a formal pledge before an official body such as a judge

Example

Hari swore that he had not taken the money from his brother's wallet.

swear + that-clause for asserting truth

Before giving evidence, witnesses must swear to tell the truth in court.

Common collocations
  • swear an oath
  • swear allegiance
  • swear secrecy
  • swear to God
  • swear on something
  • swear blind
Synonyms
  • vow

    more formal and emotional; often used for personal or religious promises

  • pledge

    formal; often used for public or political commitments

  • promise

    more general and less formal; does not carry the same weight of solemnity

  • attest

    very formal; used in legal or official contexts

Antonyms
  • deny

    to say something is not true, the opposite of asserting it under oath

Grammar Patterns

swear + that-clause

swear + to-infinitive

swear (an oath)

swear to do something

Usage Note

This sense can take a that-clause ('swear that…') for asserting truth, or a to-infinitive ('swear to do something') for promising a future action. The phrase 'swear an oath' is a fixed collocation used in legal and formal contexts. Distinguish from sense 1 (USE BAD LANGUAGE): if the object is a person, check whether 'at' follows — 'swear at someone' = curse, 'swear someone to secrecy' = make them promise.

Common Mistakes

I swear you I did not do it.
I swear (that) I did not do it.' or 'I swear to you (that) I did not do it.
'swear' does NOT take an indirect object directly; use 'to you' or a that-clause.
She swore to not tell anyone.
She swore not to tell anyone.
the negative goes before 'to' in the to-infinitive structure.
Phrasal verbs

swear by

phrasal verb

To have complete trust in something because it has worked well for you.

My grandmother swears by drinking ginger tea for a sore throat.

Diego swears by this brand of running shoes for marathons.

swear in

phrasal verb

To officially make someone take an oath when starting a new job or position.

The chief justice swore in the new president at noon.

When will the mayor be sworn in after the election?

swear into

phrasal verb

To formally admit someone to a position or group by having them take an oath.

The judge swore the new citizens into the country.

Sara was sworn into the honor society last Friday.

swear off

phrasal verb

To decide to stop doing or using something, especially a bad habit.

After his health scare, Brian swore off sugary drinks completely.

Has Maya sworn off social media for the month?

swear to

phrasal verb

To promise very seriously that something is true or that you will do something.

I can swear to the fact that I saw him at the library.

The witness swore to tell the whole truth in court.

Idioms

swear blind

idiom

To strongly insist that something is true, even if others doubt it.

Mia swore blind that she had never seen the missing keys.

Did Tom swear blind he finished the project on time?

swear like a trooper

idiom

To use a lot of very rude or offensive words when speaking.

The old sailor swore like a trooper when he stubbed his toe.

Why does your brother swear like a trooper during video games?

swear — noun

Word family

  • swear word
    nounB1
  • swearing
    nounB1
  • swearer
    nounC1
  • sworn
    adjectiveB2
  • unsworn
    adjectiveC1

Synonym discussion

Sense: verb/2

All four words involve committing to something, but they differ in weight and context. 'Swear' is the strongest — it suggests a solemn, often formal declaration (as in court or in front of witnesses) and carries moral or legal force. 'Vow' is deeply personal and emotional, often used for lifetime commitments (marriage vows, personal resolutions). 'Pledge' is more public and formal, typically used for political or institutional promises (pledging allegiance, a pledge to donate). 'Promise' is the most general and everyday word — it covers small agreements between friends up to serious commitments, but without the formal weight of 'swear'. For example: you promise to return a book, you swear to tell the truth in court, you vow to always be there for someone, and you pledge a donation to charity.

swear ↗vow ↗pledge ↗promise ↗

Common collocations

Nouns

Adverbs

Phrases

  • swear to God
  • swear blind
  • swear like a sailor
  • swear on someone's life

Prepositions

Etymology

Proto-GermanicOld EnglishMiddle EnglishEnglish

The word 'swear' comes from Old English 'swerian', meaning 'to take an oath'. This goes back to a Proto-Germanic root '*swarjanan', which is related to Latin 'respondere' (to answer). The sense of using bad language developed later from the idea of 'calling on a sacred name in a casual or angry way'.