sister

noun

sis·​ter ˈsi-stər 

1

: a female who has one or both parents in common with another

2

often capitalized

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

Serenity is survived by her parents, Daniel and Daniela Campos; sisters, Braylee and Haisley, and brother, Asher; as well as a host of other family members. —Angel Saunders, People.com, 28 Jan. 2025

Jimenez-Rico’s family had just returned home from a trip to Mexico when his dad and sister, 22-year-old Jocelyn Jimenez, started criticizing him about dirty dishes, according to records obtained by the Milwaukee Journal Sentinel. —Mitchell Willetts, Kansas City Star, 28 Jan. 2025

Yet her happiness at their reunion soon turns to terror as her sister’s influence turns her and her husband’s (Ulrich) life into a savage nightmare. —Brent Lang, Variety, 28 Jan. 2025

His older brother, Tom, also was a state qualifier at Brother Rice, and older sister Fiona, who prepped at Mother McAuley, is a junior outfielder in softball for St. Xavier. —Patrick Z. McGavin, Chicago Tribune, 28 Jan. 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

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