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

For Jennifer and Nicole Vitagliano, twin sisters and the co-founders behind buzzy Manhattan restaurants Raf’s and The Musket Room, hosting is almost always a group effort anyway. — Elly Leavitt, Vogue, 4 Sep. 2026

Under the guise of paying homage to the bouquet of flowers his grandmother crocheted for his sister on her wedding day, Joseph added a matching purple bouquet which conveniently hides the super long crotch. — Rafaela Bassili, Vulture, 4 Sep. 2026

Peyton Stewart was a 21-year-old international business major who grew up with her sister in Westwood, New Jersey, studied abroad in London and interned at TikTok. — Amanda Lee Myers, USA Today, 4 Sep. 2026

Several other concepts have closed in Park Place within the past few months, including Panache Chocolatier; Session Taco’s spinoff, LaPez ModMex; French restaurant Aixois Sud; and Bamboo Penny’s sister concept, Aqua Penny’s. — Jenna Thompson, Kansas City Star, 4 Sep. 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