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

Sam Machado and his wife, Tammy Machado, who owned the property, and Tammy Machado’s sister, Reiko Matsumura, a former Yolo County sheriff’s deputy who went on leave after the explosion and retired in September. — Daniel Lempres, Sacbee.com, 25 July 2026

During the investigation, Feliz contacted a detective and said the baby the police were searching for belonged to her sister — who told police that was a lie. — Devoun Cetoute, Miami Herald, 24 July 2026

Alanna Schermerhorn-Wallace confronted Colt directly about watching her brother’s final moments on surveillance video, while oldest sister Lilianah Ahmed tearfully recalled the agonizing wait to learn whether Mason had survived. — Isabel Rosales, CNN Money, 24 July 2026

Madeleine was three at the time, and sleeping in the apartment with Sean and his twin sister, Amelie, while their parents ate at a nearby restaurant in Praia da Luz, a resort on the western Algarve coast. — Amelie Claydon, New York Times, 24 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