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See more synonyms for sister on Thesaurus.com
  1. a female offspring having both parents in common with another offspring; female sibling.
  2. Also called half sister. a female offspring having only one parent in common with another offspring.
  3. stepsister.
  4. a female friend or protector regarded as a sister.
  5. a thing regarded as feminine and associated as if by kinship with something else: The ships are sisters.
  6. a female fellow member, as of a church.
  7. a female member of a religious community that observes the simple vows of poverty, chastity, and obedience.
  8. British. a nurse in charge of a hospital ward; head nurse.
  9. a fellow black woman.
  10. a woman who supports, promotes, or participates in feminism.
  11. Informal. a form of address used to a woman or girl, especially jocularly or contemptuously: Listen, sister, you've had enough.
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  1. being or considered a sister; related by or as if by sisterhood: sister ships.
  2. having a close relationship with another because of shared interests, problems, or the like: We correspond with school children in our sister city.
  3. Biochemistry. being one of an identical pair.
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Origin of sister

before 900; Middle English (noun) < Old Norse systir; cognate with Old English sweoster, Dutch zuster, German Schwester, Gothic swistar; akin to Serbo-Croatian sèstra, Lithuanian sesuõ, Latin soror (< *swesor), Old Irish siur, Welsh chwaer, Sanskrit svasar sister, Greek éor daughter, niece
Related formssis·ter·less, adjectivesis·ter·like, adjectivenon·sis·ter, noun, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Related Words for sister

relative, twin, relation, kin

Examples from the Web for sister

Contemporary Examples of sister

Historical Examples of sister

  • "But his sitting there eating in that—that shirt—" said his sister.

    The Spenders

    Harry Leon Wilson

  • "They needn't eat their lunch that way," declared his sister.

    The Spenders

    Harry Leon Wilson

  • It's the Viluca—Mr. Bines, you know; he's bringing his sister back to me.

    The Spenders

    Harry Leon Wilson

  • On his death-bed he charged his nephew to protect and cherish me as a sister.


    Lydia Maria Child

  • You wouldn't turn out your sister's son, would you, Uncle Paul?

    Brave and Bold

    Horatio Alger

British Dictionary definitions for sister


  1. a female person having the same parents as another person
  2. See half-sister, stepsister
  3. a female person who belongs to the same group, trade union, etc, as another or others
  4. informal a form of address to a woman or girl, used esp by Black people in the US
  5. a senior nurse
  6. mainly RC Church a nun or a title given to a nun
  7. a woman fellow member of a Church or religious body
  8. (modifier) belonging to the same class, fleet, etc, as another or othersa sister ship
  9. (modifier) biology denoting any of the cells or cell components formed by division of a parent cell or cell componentsister nuclei
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Word Origin for sister

Old English sweostor; related to Old Norse systir, Old High German swester, Gothic swistar
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for sister


mid-13c., from Old English sweostor, swuster "sister," or a Scandinavian cognate (Old Norse systir, Swedish syster, Danish søster), in either case from Proto-Germanic *swestr- (cf. Old Saxon swestar, Old Frisian swester, Middle Dutch suster, Dutch zuster, Old High German swester, German Schwester, Gothic swistar).

These are from PIE *swesor, one of the most persistent and unchanging PIE root words, recognizable in almost every modern Indo-European language (e.g. Sanskrit svasar-, Avestan shanhar-, Latin soror, Old Church Slavonic, Russian sestra, Lithuanian sesuo, Old Irish siur, Welsh chwaer, Greek eor). French soeur "a sister" (11c., instead of *sereur) is directly from Latin soror, a rare case of a borrowing from the nominative case.

According to Klein's sources, probably from PIE roots *swe- "one's own" + *ser- "woman." For vowel evolution, see bury. Used of nuns in Old English; of a woman in general from 1906; of a black woman from 1926; and in the sense of "fellow feminist" from 1912. Meaning "female fellow-Christian" is from mid-15c. Sister act "variety act by two or more sisters" is from vaudeville (1908).

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Online Etymology Dictionary, © 2010 Douglas Harper