Green’s Dictionary of Slang

1. a woman.

1900–10		Stephens & O’Brien Materials for a Dict. of Aus. Sl. [unpub. ms.] 132: SPLIT-STUFF: slang for the female commodity.
1944		O. Ferguson ‘Vocab. for Lakes, [etc.]’ AS XIX:2 104: A woman who is neither your sister nor your mother is a dingbat, a baloney, or a split-tail.
1966		R. Giallombardo Gloss. in Study of a Women’s Prison 208: Split Tail. Female; girl; broad.
1972		B. Rodgers Queens’ Vernacular 188: split belly any woman [...] Syn: split stuff [ ...] split tail.
1975		J. Wambaugh Choirboys (1976) 155: Now you’re sounding just like what this nigger-loving split tail must’ve sounded like.
1976		P. Conroy Great Santini (1977) 254: You and the other split-tails can do all the feeling you want to.
1991		Eble Campus Sl. Mar. 9: split tail – woman.
2018		T. Pluck ‘Hot Rod Heart’ in Life During Wartime 111: ‘[S]he’s pretty smarrt for a split tail’.

2. in attrib. use of sense 1, weak, effeminate.

2013

F. Bill Donnybrook [ebook] ‘Gonna shit and fall back in it, split-tail son of a bitch!’.