The Collaborative International Dictionary of English v.0.48:

Lecher \Lech"er\, n. [OE. lechur, lechour, OF. lecheor, lecheur,
   gormand, glutton, libertine, parasite, fr. lechier to lick,
   F. l['e]cher; of Teutonic origin. See Lick.]
   A man given to lewdness; one addicted, in an excessive
   degree, to the indulgence of sexual desire, or to illicit
   sexual relations with women; also called letch and lech.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Lecher \Lech"er\, v. i. [imp. & p. p. Lechered; p. pr. & vb.
   n. Lechering.]
   To practice lewdness.
   [1913 Webster]

WordNet (r) 3.0 (2006):

lecher
    n 1: man with strong sexual desires [syn: satyr, lecher,
         lech, letch]