Sissy f
English: pet form of CICELY (SEE Cicely) that came into use about 1890 but disappeared again after about 1920, no doubt because of the homonymous slang word sissy ‘effeminate’ (which is probably from the kinship term sister). In recent years it has undergone something of a revival.
Variants: Sissey, Sissie.
First names dictionary. 2012.