English Reference
verb · noun

swear

v. · n.
US /ˈswɛɹ/ UK /swˈeə/ swear UK spelling swears

infinitive swear past swore past participle sworn

  1. 01 B1 Intermediate

    v.to make a serious or legal promise that something is true or that you will do something.

    v.to make a solemn or formal declaration, often invoking a deity or legal authority, to attest to the truth of a statement.

    Simple

    I swear that I am telling the truth about what happened last night.

    In context

    The witness was required to swear an oath on the Bible before providing her testimony to the court.

    Usage

    often followed by a 'that' clause or an infinitive.

  2. 02 B2 Upper Intermediate Informal

    v.to use rude, offensive, or angry words.

    v.to use profane, obscene, or offensive language, often as an expression of anger or frustration.

    Simple

    He started to swear loudly when he dropped the heavy box on his foot.

    In context

    The coach was warned by the referee after he continued to swear at the players from the sidelines.

    Usage

    intransitive or followed by 'at' when directed at a person.

    curseblaspheme
  3. 03 C1 Advanced Informal

    v.to believe strongly that something is effective or useful.

    v.to express great confidence in the effectiveness or value of a particular thing.

    Simple

    My grandmother swears by honey and lemon whenever she has a sore throat.

    In context

    Many professional athletes swear by this specific recovery routine, claiming it significantly reduces the risk of muscle strain.

    Usage

    usually used in the phrasal form 'swear by'.

  4. 04 B2 Upper Intermediate British EnglishInformal

    n.a rude or offensive word.

    n.an instance of profane or obscene language; a swear word.

    Simple

    The young boy got in trouble for using a swear in front of his teacher.

    In context

    The script was edited for television to remove every swear and replace them with milder alternatives.

    Teacher's tip

    In American English, 'curse word' or 'profanity' is more common than using 'swear' as a noun.

    profanitycurse wordexpletive

When the talks broke down a week ago, there was no shouting, no name-calling, no swearing or denunciations.

Toronto Sun· 28 Aug 2026

I notice he doesn’t swear and I ask if he’s religious.

The Guardian· 24 Aug 2026

Etymology 1

From Middle English sweren, swerien, from Old English swerian (“to swear, take an oath of office”), from Proto-West Germanic swarjan, from Proto-Germanic swarjaną (“to speak, swear”), from Proto-Indo-European *swer- (“to swear”). Cognate with West Frisian swarre (“to swear”), Saterland Frisian swera (“to swear”), Dutch zweren (“to swear, vow”), Low German swören (“to swear”), sweren, German schwören (“to swear”), Danish sværge, Swedish svära (“to swear”), Icelandic sverja (“to swear”), Russian свара (svara, “quarrel”). Also cognate to Albanian var (“to hang, consider, to depend from”) through Proto-Indo-European. The original sense in all Germanic languages is “to take an oath”. The sense “to use bad language” developed in Middle English and is based on the Christian prohibition against swearing in general (cf. Matthew 5:33-37) and invoking God’s name in particular (i.e. frequent swearing was considered similar to the use of obscene words).

Etymology 2

From the above verb, or from Middle English sware, from Old English swaru, from Proto-Germanic *swarō.

Etymology 3

From Middle English swere, swer, swar, from Old English swǣr, swār (“heavy, heavy as a burden, of great weight, oppressive, grievous, painful, unpleasant, sad, feeling or expressing grief, grave, slow, dull, sluggish, slothful, indolent, inactive from weakness, enfeebled, weak”), from Proto-West Germanic swār, from Proto-Germanic swēraz (“heavy”), from Proto-Indo-European *swer- (“heavy”). Cognate with West Frisian swier (“heavy”), Dutch zwaar (“heavy, hard, difficult”), German schwer (“heavy, hard, difficult”), Danish svær (“heavy, hard, severe”), Swedish svår (“heavy, hard, severe”), Latin sērius (“earnest, grave, solemn, serious”) and Albanian varrë (“wound, plague”).

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

This entry
Origin ine-pro *swer-
Level B2 · Upper Intermediate
Frequency Common
Updated