The Collaborative International Dictionary of English v.0.48:

Drivel \Driv"el\, v. i. [imp. & p. p. Driveledor Drivelled;
   p. pr. & vb. n. Driveling or Drivelling.] [Cf. OE.
   dravelen, drabelen, drevelen, drivelen, to slaver, and E.
   drabble. Cf. Drool.]
   1. To slaver; to let spittle drop or flow from the mouth,
      like a child, idiot, or dotard.
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   2. [Perh. a different word: cf. Icel. drafa to talk thick.]
      To be weak or foolish; to dote; as, a driveling hero;
      driveling love. --Shak. Dryden.
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The Collaborative International Dictionary of English v.0.48:

Drivel \Driv"el\, n.
   1. Slaver; saliva flowing from the mouth.
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   2. Inarticulate or unmeaning utterance; foolish talk; babble.
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   3. A driveler; a fool; an idiot. [Obs.] --Sir P. Sidney.
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   4. A servant; a drudge. [Obs.] --Huloet.
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WordNet (r) 3.0 (2006):

drivel
    n 1: a worthless message [syn: drivel, garbage]
    2: saliva spilling from the mouth [syn: drool, dribble,
       drivel, slobber]
    v 1: let saliva drivel from the mouth; "The baby drooled" [syn:
         drivel, drool, slabber, slaver, slobber,
         dribble]