1768, "sister," a colloquial extended form of sis (q.v.). The meaning "effeminate man" is recorded by 1873; the adjective in this sense is from 1891 (sissyish is attested from 1880); hence sissy bar, recorded from 1969. Also in 19c. sometimes a women's or girl's name, short for Cecilia, Priscilla, etc.). Related: Sissiness.
updated on November 20, 2022