sister

American  

[sis-ter] / ˈsɪs tər /

noun

• sisters
  plural

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

Derived Forms

• nonsister
  noun
• sisterless
  adjective
• sisterlike
  adjective

Inflected Forms

Nouns

• sisters
  plural

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

See Examples For:

sister sisters

In Eastbourne, Michael Simpson watched the eclipse with his daughter Chloe, and his sister, Anne.

From BBC ● Aug. 13, 2026

Her mother, 72-year-old Luz Marina, recently suffered a thrombosis, and her sister Sandra, 38, ended up in a wheelchair because of meningitis.

From Barron's ● Aug. 11, 2026

Newly minted incumbent Darline Graham, the sister of Lindsey, was appointed to the seat initially as a placeholder.

From Slate ● Aug. 11, 2026

Janet Patten, Martin’s younger sister, flew in from New Jersey to support him.

From Los Angeles Times ● Aug. 10, 2026

Before I can stop myself, I ask, ‘Did you have a sister?’

From "Code Name Kingfisher" by Liz Kessler

Catholic sisters are playing a key role among clergy and other religious leaders who have been organizing demonstrations and vigils at ICE field offices and processing centers in places like Chicago, Pittsburgh and Philadelphia.

From Salon ● Aug. 12, 2026

The group of sisters positioned on the corner in front of the office were from different orders: Sisters of Mercy, Sisters of the Precious Blood, Sisters of Charity and Sisters of Divine Providence.

From Salon ● Aug. 12, 2026

Det Con Rebecca Lovekin said the sisters had shown "immeasurable courage, support and heart during these proceedings".

From BBC ● Aug. 10, 2026

This is the first time the Williams sisters will compete at the Cincinnati Open together as a team.

From Los Angeles Times ● Aug. 5, 2026

He glanced out the bright windows, then boomed, “Even the sunshine is somber today, brothers and sisters, when we see Miss Myrt Arbuckle on her final journey, as she swaps semesters for eternity.”

From "The Teacher’s Funeral" by Richard Peck

Related Words

• relative
• twin