(slang, humorous) A man's hand, used for masturbation.

The half sister of one's spouse. / The wife of one's half-sibling. / The wife of the half-sibling of one's spouse.

One's spouse's sister-in-law, especially one's husband's brother's wife, one's brother's wife in relation to the spouses of his siblings; either of two (or more) women who are married to brothers, in relation to the other.

(genetics) The coupling of replicated sister chromatids along the whole length of a chromosome

Alternative spelling of three-quarter sister

(horse breeding) The female offspring of a horse's sire/dam that is by/out of a sibling of its other parent. / (horse breeding) The female offspring of a horse's dam and a son of its sire.

(US politics) A politician's public repudiation of extremism perceived to be allied or associated with them or their political party.

plural of Sister Souljah moment

The sister of one's boyfriend or girlfriend. / Girlfriend of one's brother or sister. / The sister of one's ex-spouse.

Used to ask whether someone has any siblings.