Dictionary

sister

noun sis·ter \ˈsis-tər\

: a girl or woman who has one or both of the same parents as you

—used when talking to a woman

: a member of a religious community of women

Full Definition of SISTER

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

  1. The sisters live in the convent.

Origin of SISTER

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 12th century

sister

noun sis·ter \ˈsis-tər\   (Medical Dictionary)

Medical Definition of SISTER

chiefly British :  a head nurse in a hospital ward or clinic; broadly :  nurse
May 24, 2015
erudite Hear it
learned or pedantic
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