A horse; a pretty little tit; a smart little girl. a *** or tid bit; a delicate morsel. Tommy tit; a smart lively little fellow.
Definition taken from The 1811 Dictionary of the Vulgar Tongue, originally by Francis Grose.
Tiring * Tit For TatNathan Bailey's 1736 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes