Sissie is a variant of the name Sissy, which is often used as a diminutive or affectionate form of the name Cecilia or Frances. The name Sissy itself is derived from the Latin name Cecilia, meaning 'blind' or 'dim-sighted,' and has been used historically as a term of endearment. Sissie carries a similar connotation of warmth and familiarity, often used in informal or familial contexts.