"make (a male) effeminate or more effeminate," 1897 (implied in sissified), American English, from sissy + -fy. Related: Sissifying; sissification (1915).
Entries linking to sissify
sissy n.
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.
-fy
word-forming element meaning "make, make into," from French -fier, from Latin -ficare, combining form of facere "to make" (from PIE root *dhe- "to set, put").