sister
Americannoun
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sisters
plural
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a female offspring having both parents in common with another offspring; female sibling.
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Also called half sister. a female offspring having only one parent in common with another offspring.
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a female friend or protector regarded as a sister.
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a thing regarded as feminine and associated as if by kinship with something else.
The ships are sisters.
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a female fellow member, as of a church.
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a female member of a religious community that observes the simple vows of poverty, chastity, and obedience.
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British. a nurse in charge of a hospital ward; head nurse.
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Informal. a term used to refer to or address a fellow Black woman; soul sister.
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a woman who supports, promotes, or participates in feminism.
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Informal. a form of address used to a woman or girl, especially jocularly or contemptuously.
Listen, sister, you've had enough.
adjective
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being or considered a sister; related by or as if by sisterhood.
sister ships.
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having a close relationship with another because of shared interests, problems, or the like.
We correspond with school children in our sister city.
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Biochemistry. being one of an identical pair.
noun
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a female person having the same parents as another person
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a female person who belongs to the same group, trade union, etc, as another or others
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informal a form of address to a woman or girl, used esp by Black people in the US
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a senior nurse
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RC Church a nun or a title given to a nun
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a woman fellow member of a Church or religious body
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(modifier) belonging to the same class, fleet, etc, as another or others
a sister ship
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(modifier) biology denoting any of the cells or cell components formed by division of a parent cell or cell component
sister nuclei
Other Word Forms
Derived Forms
Inflected Forms
Nouns
Etymology
Origin of sister
First recorded before 900; Middle English (noun) from Old Norse systir; cognate with Old English sweoster, Dutch zuster, German Schwester, Gothic swistar; akin to Serbo-Croatian sèstra, Lithuanian sesuõ, Latin soror (from unattested swesor ), Old Irish siur, Welsh chwaer, Sanskrit svasar “sister,” Greek éor “daughter, niece”
Explanation
Your sister is your female sibling. If your parents have six children, and all of them are girls, that means you have five sisters. Your biological sister has the same mother and father that you have, but some sisters are adopted, or even have a different mom or dad (some people call this a stepsister or a half-sister). If you join a college sorority or a trade union, you'll refer to the other members as your sisters. Catholic nuns and other religious women are also called sisters. The roots of sister go back to words meaning "one's own" and "woman."
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
See Examples For:
Khan's personal physician Faisal Sultan, and sister and medical doctor Uzma Khan, "shall be permitted to remain associated with the prisoner's medical examination and treatment".
From Barron's ● Aug. 18, 2026
In a statement released on Tuesday to mark the new book, Earl Spencer said he had been "inundated yet again" with requests for interviews about his sister, with the 30th anniversary of her death approaching.
From BBC ● Aug. 18, 2026
“Especially my 93-year-old brother and my 95-year-old sister that are here. This is a very, very special day.”
From Los Angeles Times ● Aug. 16, 2026
Our new friend moved me to think that we’re all works in progress—even those of us, like my sister, who are deep in the challenges of aging.
From The Wall Street Journal ● Aug. 16, 2026
Certainly not with the sister where they could so easily be traced.
From "The Hiding Place" by Corrie ten Boom
The Delevingne sisters decorated the 1955-midcentury property together before handing the keys over to Usher.
From MarketWatch ● Aug. 18, 2026
The sisters last played together at the 2022 US Open, which was Serena's final tournament before she "evolved away" from tennis.
From BBC ● Aug. 18, 2026
Two of Rani’s older sisters have government jobs, an enormous help for her farming family.
From The Wall Street Journal ● Aug. 15, 2026
This arrangement can make sisters more closely related to one another than they are to their own offspring.
From Science Daily ● Aug. 15, 2026
Kate also admitted that sometimes the sisters brought in helpers.
From "American Spirits" by Barb Rosenstock
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
