Sissy
来自Big Physics
mid 18th century (in the sense ‘sister’): from sis1 + -y2.
wiktionary
From sis + -y.
Likely onomatopoetic, perhaps related to French pipi(“urine”). Compare piss; wee-wee.
Clipping of sissygasm.
etymonline
sissy (n.)
1768, "sister," colloquial extended form of sis (q.v.). Meaning "effeminate man" is recorded by 1873; the adjective in this sense is from 1891. Also in 19c. sometimes a women's or girl's name, short for Cecilia, Priscilla, etc.). Related: Sissiness. Sissy bar is recorded from 1969.