The Collaborative International Dictionary of English v.0.48:

Driveler \Driv"el*er\, n.
   A slaverer; a slabberer; an idiot; a fool. [Written also
   driveller.]
   [1913 Webster]

WordNet (r) 3.0 (2006):

driveller
    n 1: someone whose talk is trivial drivel [syn: driveller,
         jabberer]
    2: a person who dribbles; "that baby is a dribbler; he needs a
       bib" [syn: dribbler, driveller, slobberer, drooler]