The Collaborative International Dictionary of English v.0.48:

Adviser \Ad*vis"er\, n.
   One who advises.
   [1913 Webster]

WordNet (r) 3.0 (2006):

adviser
    n 1: an expert who gives advice; "an adviser helped students
         select their courses"; "the United States sent military
         advisors to Guatemala" [syn: adviser, advisor,
         consultant]

Moby Thesaurus II by Grady Ward, 1.0:

52 Moby Thesaurus words for "adviser":
   Dutch uncle, Polonius, admonisher, announcer, annunciator,
   authority, backseat driver, buttinsky, channel, cicerone,
   communicant, communicator, confidant, confidante, consultant,
   counsel, counselor, enlightener, expert, expert witness,
   gossipmonger, grapevine, guide, informant, information center,
   information medium, informer, instructor, interviewee, kibitzer,
   meddler, mentor, monitor, mouthpiece, nestor, newsmonger, notifier,
   orienter, preceptist, press, public relations officer, publisher,
   radio, reporter, source, spokesman, teacher, television, teller,
   tipster, tout, witness