sister

American  

[sis-ter] / ˈsɪs tər /

noun

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. Informal. a term used to refer to or address a fellow Black woman; soul sister.

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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adjective

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.

sister British  

/ ˈsɪstə /

noun

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. 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 others

   a sister ship

9. (modifier) biology denoting any of the cells or cell components formed by division of a parent cell or cell component

   sister nuclei

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Other Word Forms

• nonsister noun
• sisterless adjective
• sisterlike adjective

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”

Example Sentences

Iacocca’s turnaround worked, bolstered by the launch of a successful minivan line under sister brands Dodge and Plymouth.

From The Wall Street Journal • Apr. 4, 2026

Don’t miss: My husband is giving me 75% of his trust — and allocating 25% to his sister.

From MarketWatch • Apr. 3, 2026

Her sister, Yolanda “Yola” Honda, 82, was staying at the house and helping her with the recovery.

From Los Angeles Times • Apr. 1, 2026

Their sister, Alice Walton, is ranked No. 13, with wealth of $142 billion.

From Barron's • Apr. 1, 2026

I was condemned to eternal perdition if I was going to be able to call my own sister ‘Miss Tansy.’

From "The Teacher’s Funeral" by Richard Peck

Related Words

• relative
• twin