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

Her candidacy has focused on her working-class roots and role as a caretaker for a disabled sister. —Alice Yin, Chicago Tribune, 18 Mar. 2026

Kathy Beeck, left, and her sister Robin Beeck are cofounders of the Boulder International Film Festival. —Libby Smith, CBS News, 18 Mar. 2026

Veronica Gutierrez brought her husband, her sister and her mother for support, but when grainy security footage began to play during the prosecutor’s opening statement Monday, their sobs drowned out his voice. —Julia Prodis Sulek, Mercury News, 17 Mar. 2026

Arriving at his parents’ house, which overflowed with relatives — brothers, sisters, aunts, and uncles — Gary took in all the Stewarts. —Jonathan Bernstein, Rolling Stone, 17 Mar. 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