sister

noun

sis·​ter ˈsi-stər 

1

: a female who has one or both parents in common with another

2

often Sister

a

: a member of a women's religious order (as of nuns or deaconesses)

especially : one of a Roman Catholic congregation under simple vows

b

: a girl or woman who is a member of a Christian church

3

a

: a girl or woman regarded as a comrade

b

: a girl or woman who shares with another a common national or racial origin

especially : a Black girl or woman

4

: one that is closely similar to or associated with another

sister cities

5

chiefly British : nurse

6

a

: girl, woman

b

: person

—usually used in the phrase weak sister

7

: a member of a sorority

Examples of sister in a Sentence

The sisters live in the convent.

Recent Examples on the Web

Little Notes • Laura sees that Mary is still upset by what happened at the James house and attempts to smooth things over with a cookie and acknowledging how awful the twins are, but Mary isn’t ready to forgive her sister just yet. — Maggie Fremont, Vulture, 11 July 2026

Last week’s Apple Loop can be read here, or this week’s edition of Loop’s sister column, Android Circuit, is also available on Forbes. — Ewan Spence, Forbes.com, 11 July 2026

Arngrim, 64, has a blink-and-you’ll-miss-it (yet still unforgettable) moment in Episode 2 of the Netflix series playing Ida, a forest drifter who meets up with Laura (Alice Halsey) and her older sister Mary (Skywalker Hughes). — Bryan Alexander, USA Today, 11 July 2026

The mother, Yadira, applied for asylum and listed Wilber, who was 15 at the time, and his younger sister, as dependents of her case. — Itzel Luna, Los Angeles Times, 10 July 2026

Word History

Etymology

Middle English suster, sister, partly from Old English sweostor and partly from Old Norse systir sister; akin to Latin soror sister, Sanskrit svasṛ

First Known Use

before the 12th century, in the meaning defined at sense 1

Phrases Containing sister

• big sister
• brother/sister/comrade in arms
• foster brother/sister
• half sister
• little brother/sister
• sister chromatid
• sister city
• sister-in-law
• sob sister
• soul sister
• weak sister

Rhymes for sister

• blister
• lyster
• mister
• twister
• resister
• resistor
• stepsister
• transistor

Kids Definition

sister

noun

sis·​ter ˈsis-tər 

1

: a female who has one or both parents in common with another individual

2

often capitalized : a member of a religious community of women : nun

3

a

: a fellow female member of a group

b

: a girl or woman who shares a common national or racial origin with another

4

: one that is closely similar to or associated with another

sister schools

sister ships

5

chiefly British : nurse entry 1 sense 2

sisterly adjective or adverb

Medical Definition

sister

noun

sis·​ter ˈsis-tər 

chiefly British

: a head nurse in a hospital ward or clinic

broadly : nurse