The Collaborative International Dictionary of English v.0.48:

Lecturer \Lec"tur*er\ (-[~e]r), n.
   One who lectures; an assistant preacher.
   [1913 Webster]

WordNet (r) 3.0 (2006):

lecturer
    n 1: a public lecturer at certain universities [syn: lector,
         lecturer, reader]
    2: someone who lectures professionally

The Devil's Dictionary (1881-1906):

LECTURER, n.  One with his hand in your pocket, his tongue in your ear
and his faith in your patience.