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

When an accident temporarily shuttered a beloved In-A-Tub’s doors and injured the owner, dedicated customers showed their support for the restaurant known for its neon-orange powdered cheese by dining at its sister location across town and donating to a GoFundMe for the owner. —Jenna Ebbers, Kansas City Star, 10 Mar. 2026

The spa Origins Astral doesn’t have its own spa but guests can access the Laka-Tii Spa Suite at sister hotel Origins Floral. —Condé Nast, Condé Nast Traveler, 10 Mar. 2026

Castel-Orozco told her sister that Contreras-Mujica wanted to end the relationship in December 2024, the month before her fatal shooting, the affidavit stated. —Lauren Penington, Denver Post, 10 Mar. 2026

Piehsak has six brothers and sisters, and their mother is at a loss because her husband, the only one who can drive the heavy tractor, was called up to join a unit at the frontline. —John Vink, The Dial, 10 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