Source : Webster's Revised Unabridged Dictionary (1913)

Letch \Letch\ (l[e^]ch), v. & n.
   See {Leach}.

Letch \Letch\, n. [See {Lech}, {Lecher}.]
   Strong desire; passion. (Archaic).

Source : WordNet®

letch
     n : man with strong sexual desires [syn: {satyr}, {lecher}, {lech}]