The Collaborative International Dictionary of English v.0.48:

Froth \Froth\, v. t. [imp. & p. p. Frothed; p. pr. & vb. n..
   Frothing.]
   1. To cause to foam.
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   2. To spit, vent, or eject, as froth.
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            He . . . froths treason at his mouth. --Dryden.
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            Is your spleen frothed out, or have ye more?
                                                  --Tennyson.
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   3. To cover with froth; as, a horse froths his chain.
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The Collaborative International Dictionary of English v.0.48:

Froth \Froth\, v. i.
   To throw up or out spume, foam, or bubbles; to foam; as beer
   froths; a horse froths.
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The Collaborative International Dictionary of English v.0.48:

Froth \Froth\, n. [OE. frothe, Icel. fro[eth]a; akin to Dan.
   fraade, Sw. fradga, AS. [=a]freo[eth]an to froth.]
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   1. The bubbles caused in fluids or liquors by fermentation or
      agitation; spume; foam; esp., a spume of saliva caused by
      disease or nervous excitement.
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   2. Any empty, senseless show of wit or eloquence; rhetoric
      without thought. --Johnson.
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            It was a long speech, but all froth.  --L'Estrange.
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   3. Light, unsubstantial matter. --Tusser.
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   Froth insect (Zool.), the cuckoo spit or frog hopper; --
      called also froth spit, froth worm, and froth fly.


   Froth spit. See Cuckoo spit, under Cuckoo.
      [1913 Webster]

WordNet (r) 3.0 (2006):

froth
    n 1: a mass of small bubbles formed in or on a liquid; "the beer
         had a thick head of foam" [syn: foam, froth]
    v 1: become bubbly or frothy or foaming; "The boiling soup was
         frothing"; "The river was foaming"; "Sparkling water" [syn:
         foam, froth, fizz, effervesce, sparkle, form
         bubbles]
    2: make froth or foam and become bubbly; "The river foamed"
       [syn: froth, spume, suds]
    3: exude or expel foam; "the angry man was frothing at the
       mouth"

Moby Thesaurus II by Grady Ward, 1.0:

132 Moby Thesaurus words for "froth":
   aerate, air, alluvion, alluvium, ash, babble, beat, breakers,
   bric-a-brac, bubble, bubbles, chaff, chicken feed, chickenshit,
   chip, cinder, clinker, cobweb, collar, cork, cream, deposition,
   deposits, details, diluvium, down, draff, dregs, dribble, drivel,
   drool, dross, dust, effervesce, ember, ether, expectoration, fairy,
   feather, feces, fizz, flippancy, flue, fluff, foam, frivolity,
   fuzz, gab, gas, gibberish, gimcrackery, gossamer, grounds, head,
   hot air, knickknackery, lather, lees, levity, lightness, loess,
   mantle, meringue, minutiae, moraine, mote, mousse, mouth-watering,
   nonsense, offscum, peanuts, piffle, plash, precipitate,
   precipitation, ptyalism, puff, rubbish, saliva, salivate,
   salivation, scoria, scud, scum, sea foam, sediment, settlings,
   shower, sialagogue, silt, sinter, slabber, slag, slaver, slobber,
   slosh, small beer, small change, smut, soapsuds, soot, souffle,
   sparge, spatter, spindrift, spit, spittle, splash, splatter,
   sponge, spoondrift, spray, sprinkle, spume, sputum, stinging,
   straw, sublimate, sud, suds, surf, swash, thistledown, trash,
   trifles, trivia, trumpery, twaddle, whip, whisk, white water,
   yeast