Webster’s Revised Unabridged Dictionary · 1913
Wittol
Wit′tol (·tŭl), n. [Said to be for white tail, and so called in allusion to its white tail; but cf. witwal.]
1. (Zoöl.) The wheatear. [Prov. Eng.]
2. A man who knows his wife's infidelity and submits to it; a tame cuckold; — so called because the cuckoo lays its eggs in the wittol's nest. [Obs.] Shak.