Jealous lover's term for female sexual partner suspected of courting infidelity, on the basis that she dresses in her most revealing, snittiest outfit whenever she's going off for "a night with the girls". See also snit, snitter. Could be derived from SNeaky and bITchy, but definitely Copyright Moi circa 1992. I have witnesses.
With her low-cut top and fishnet stockings, she's looking like a right snitterbitch. Oh yeh baby. Uh-huh.