The Collaborative International Dictionary of English v.0.48:
Sis \Sis\, n. A colloquial abbreviation of Sister. [1913 Webster]The Collaborative International Dictionary of English v.0.48:
Sis \Sis\, n. Six. See Sise. [Obs.] --Chaucer. [1913 Webster] Sisal grassWordNet (r) 3.0 (2006):
sis n 1: a female person who has the same parents as another person; "my sister married a musician" [syn: sister, sis] [ant: blood brother, brother]