cousin (English)

Where does "cousin" come from?

The English noun 'cousin' comes from Middle English 'cosin'[1]. This traveled through Anglo-Norman and Old French 'cosin' and 'cosine'[1], which meant 'collateral male or female relative more distant than one's brother or sister' and served as a monarch's form of address for nobles[1]. These descended from Latin 'cōnsobrīnus'[1], meaning 'maternal cousin' or 'first cousin'[1], possibly through Vulgar Latin '*cōsuīnus'[1]. The Latin term combines the prefix 'con-' with 'sobrīnus'[1], which originates from Proto-Italic '*swezrīnos' meaning 'of or belonging to a sister'[1]. This traces back to the Proto-Indo-European '*swésōr'[1], meaning 'sister'[1], built from elements meaning 'self' and 'blood'[3].

Open questions

The derivation from Latin cōnsobrīnus may have passed through an intermediate Vulgar Latin form like *cōsobīnus and then *cōsuīnus. [1] [4]
The initial so- sound in Latin sobrīnus is understood as an analogical renewal from soror rather than a regular sound change. [7]
The Proto-Indo-European word for sister may have derived from terms meaning self and blood, literally signifying a woman of one's own kin group, or alternatively from self combined with a feminine suffix. [3]

Full etymology tree

cousin (English), 'Chiefly with a qualifying word: Any relation (especially a distant one) who is not a direct ancestor or descendant but part of a person's extended family; a kinsman or kinswoman.'
- derived cosin (Middle English), 'alternative form of cosyn'
  - inherited cosen (Anglo-Norman)
    - inherited cosin (Old French), 'cousin'
      - inherited consobrinus (Latin), 'a first cousin, cousin-german'
        inherited *cōsuīnus (Vulgar Latin)
        inherited *cōsobīnus (Vulgar Latin)
        prefix con- (Latin), 'Used in compounds to indicate a being or bringing together of several objects'
        derived sobrinus (Latin), 'sororal nephew'
        derived *swezrīnos (Proto-Italic), 'of/belonging to the sister'
        inherited *swezōr (Proto-Italic), 'sister'
        inherited *swésōr (Proto-Indo-European), 'sister'
        derived *swé (Proto-Indo-European), 'self (reflexive pronoun)'
        derived *h₁ésh₂r̥ (Proto-Indo-European), 'blood'
        suffix *-sōr (Proto-Indo-European), 'Derives feminine gender stems from roots'
        influence soror (Latin), 'sister'

Ancestors

cosin (Middle English)
cosin (Old French)
cosine (Old French)
consobrinus (Latin)
*swezrīnos (Proto-Italic)
*swésōr (Proto-Indo-European)

Cognates and doublets

cousin (French)
cousine (French)
soror (Latin)

Descendants and derived words

autistics and cousins (English)
cater-cousin (English)
country cousin (English)
cous (English)
cous (English)
cousinal (English)
cousincest (English)
cousinfucker (English)
cousinfucking (English)
cousinhood (English)
cousin humper (English)
Cousin John (English)

Sources

Updated August 2026

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Etymology data from Wiktionary, CC BY-SA 4.0 · About Miraris