Etymograph

English

sister

Sister comes from Middle English suster, from Old English sweostor, from Proto-Germanic *swestēr, from Proto-Indo-European *swésōr.

  1. Proto-Indo-Europeanc. 4500–2500 BCE*swésōr1‘sister’reconstructed
  2. Proto-Germanicc. 500 BCE–200 CE*swestēr1‘sister’reconstructed
  3. Proto-West Germanicc. 200–500 CE*swester1‘sister’reconstructed
  4. Old Englishc. 450–1150sweostor1‘sister’
  5. Middle Englishc. 1150–1500suster2‘sister’
  6. Englishearliest quotation c. 1607–1608sister2

attested reconstructed ? uncertain or disputed deepest recorded ancestor

  1. 1 Wiktionary, Middle English suster
  2. 2 Wiktionary, English sister
  3. Earliest quotation in Wiktionary’s entry: c. 1607–1608, William Shakespeare, The Late: “Deep clerks she dumbs; and with her needle composes…”.

Lineage

  1. Proto-Indo-Europeanc. 4500–2500 BCE*swésōrWiktionary, Middle English suster‘sister’reconstructed
  2. Proto-Germanicc. 500 BCE–200 CE*swestērWiktionary, Middle English suster‘sister’reconstructed
  3. Proto-West Germanicc. 200–500 CE*swesterWiktionary, Middle English suster‘sister’reconstructed
  4. Old Englishc. 450–1150sweostorWiktionary, Middle English suster‘sister’
  5. Middle Englishc. 1150–1500susterWiktionary, English sister‘sister’
  6. Englishearliest quotation c. 1607–1608sisterWiktionary, English sister. Earliest quotation in Wiktionary’s entry: c. 1607–1608, William Shakespeare, The Late: “Deep clerks she dumbs; and with her needle composes…”

The story

In standard English, the form with i is due to contamination with Old Norse systir (‘sister’). The plural sistren is from Middle English sistren, a variant plural of sister, suster (‘sister’); compare brethren. The sense for "Adelpha-genus butterfly" is a semantic loan from translingual Adelpha, itself from Ancient Greek ἀδελφή (adelphḗ, “sister”).

Full etymology on Wiktionary

Word family

English words that share an ancestor with sister, grouped by the ancestor they share, most familiar first.

through Proto-Indo-European *swésōr

  • cousin ← cosyn ← cosin ← cōnsobrīnus ← sobrīnus
  • sorority ← sorōritās ← soror ← *swezōr

9 more relatives in the full family tree

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Today it means

noun A daughter of the same parents as another person; a female sibling.

Sources

Sources: Wiktionary, “sister”; the older steps come from the Wiktionary entry for Middle English suster. 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 *swésōr / sister