Etymograph

English

swear

Swear comes from Middle English sweren ‘to take an oath that an assertion is true’, from Proto-West Germanic *swarjan ‘to swear’, and ultimately from Proto-Indo-European *swer-.

  1. Proto-Indo-Europeanc. 4500–2500 BCE*swer-1‘to swear’reconstructed
  2. Proto-Germanicc. 500 BCE–200 CE*swarjaną1‘to speak’reconstructed
  3. Proto-West Germanicc. 200–500 CE*swarjan1‘to swear’reconstructed
  4. Old Englishc. 450–1150swerian1‘to swear’
  5. Middle Englishc. 1150–1500sweren1‘to take an oath that an assertion is true’
  6. Englishearliest quotation 1920swear1

attested reconstructed ? uncertain or disputed deepest recorded ancestor

  1. 1 Wiktionary, English swear
  2. Earliest quotation in Wiktionary’s entry: 1920, Mary Roberts Rinehart, Avery Hopwood: “The Bat—they called him the Bat.[…]. He'd never been…”.

Lineage

  1. Proto-Indo-Europeanc. 4500–2500 BCE*swer-Wiktionary, English swear‘to swear’reconstructed
  2. Proto-Germanicc. 500 BCE–200 CE*swarjanąWiktionary, English swear‘to speak’reconstructed
  3. Proto-West Germanicc. 200–500 CE*swarjanWiktionary, English swear‘to swear’reconstructed
  4. Old Englishc. 450–1150swerianWiktionary, English swear‘to swear’
  5. Middle Englishc. 1150–1500swerenWiktionary, English swear‘to take an oath that an assertion is true’
  6. Englishearliest quotation 1920swearWiktionary, English swear. Earliest quotation in Wiktionary’s entry: 1920, Mary Roberts Rinehart, Avery Hopwood: “The Bat—they called him the Bat.[…]. He'd never been…”

The story

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. Matthew 5:33-37) and invoking God’s name in particular (i.e. frequent swearing was considered similar to the use of obscene words).

Full etymology on Wiktionary

Linked words

through Proto-Indo-European *swer- ‘to swear’

answer, swarm, 19 more

through Proto-Germanic *swarjaną ‘to speak, swear’

sworn, 2 more

Another origin of swear

  1. Proto-Indo-Europeanc. 4500–2500 BCE*swer-‘to say, speak, talk, swear, curse’reconstructed
  2. Proto-Germanicc. 500 BCE–200 CE*swarō‘a solemn statement or affirmation’reconstructed
  3. Old Englishc. 450–1150swaru‘an oath, vow’
  4. Middle Englishc. 1150–1500sware‘a response to a query or questioning’
  5. Englishtodayswear

Another origin of swear

  1. Proto-Indo-Europeanc. 4500–2500 BCE*swer-‘heavy’reconstructed
  2. Proto-Germanicc. 500 BCE–200 CE*swēraz‘heavy’reconstructed
  3. Proto-West Germanicc. 200–500 CE*swār‘heavy’reconstructed
  4. Old Englishc. 450–1150swǣr‘heavy’
  5. Middle Englishc. 1150–1500swere‘weighing a large amount’
  6. Englishtodayswear

Today it means

verb To take an oath, to promise intensely, solemnly, and/or with legally binding effect.

Sources

Sources: Wiktionary, “swear”. By Wiktionary contributors, CC BY-SA 4.0, via kaikki.org (dump of Oct 3 2026); text adapted and restructured. Language periods are conventional ranges, not dates for this word. License.

Etymograph / Proto-Indo-European *swer- / swear

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