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

There was also an all-female 2018 spinoff Ocean's 8, starring Sandra Bullock as Danny's sister Debbie, along with Cate Blanchett, Rihanna, Helena Bonham Carter, Sarah Paulson, Awkwafina, Mindy Kaling, and Anne Hathaway. —Sydney Bucksbaum, Entertainment Weekly, 31 Dec. 2025

Koolaburra Burree Platform Slippers These slippers from Ugg’s sister brand Koolaburra are the most versatile. —Kaelin Dodge, InStyle, 30 Dec. 2025

After that, Flora lived for a time with Quentin’s half-sister, the fiercely independent Alice Roosevelt Longworth, in Washington, DC, volunteering at the Women’s Republican Committee in the office of former congressman Ruth McCormick. —Fiona Donovan, Vanity Fair, 30 Dec. 2025

Catt’s childhood, clouded by her troubled younger sister, Carla, who suffers from something like undiagnosed autism, is not a happy one. —Rosa Lyster, Harpers Magazine, 30 Dec. 2025

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