Tit

n. [Cf. Icel. tita, a tender thing.]

1. A small horse; also, in contempt, a woman.
2. [Cf. Eng. TEAT and TITMOUSE.] A small bird; a titmouse, or tomtit.
3. A morsel; a bit. [Prov. Eng.] Halliwell.

Tit for tat, an equivalent.