The Collaborative International Dictionary of English v.0.48:

Foam \Foam\ (f[=o]m), v. t.
   To cause to foam; as, to foam the goblet; also (with out), to
   throw out with rage or violence, as foam. "Foaming out their
   own shame."                                    --Jude 13.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Foam \Foam\ (f[=o]m), n. [OE. fam, fom, AS. f[=a]m; akin to OHG.
   & G. feim.]
   The white substance, consisting of an aggregation of bubbles,
   which is formed on the surface of liquids, or in the mouth of
   an animal, by violent agitation or fermentation; froth;
   spume; scum; as, the foam of the sea.
   [1913 Webster]

   Foam cock, in steam boilers, a cock at the water level, to
      blow off impurities.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Foam \Foam\ (f[=o]m), v. i. [imp. & p. p. Foamed (f[=o]md); p.
   pr. & vb. n. Foaming.] [AS. f[=ae]man. See Foam, n.]
   1. To gather foam; to froth; as, the billows foam.
      [1913 Webster]

            He foameth, and gnasheth with his teeth. --Mark ix.
                                                  18.
      [1913 Webster]

   2. To form foam, or become filled with foam; -- said of a
      steam boiler when the water is unduly agitated and frothy,
      as because of chemical action.
      [1913 Webster]

WordNet (r) 3.0 (2006):

foam
    n 1: a mass of small bubbles formed in or on a liquid; "the beer
         had a thick head of foam" [syn: foam, froth]
    2: a lightweight material in cellular form; made by introducing
       gas bubbles during manufacture
    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]

Moby Thesaurus II by Grady Ward, 1.0:

151 Moby Thesaurus words for "foam":
   Foamite, acid, aerate, air, alabaster, automatic sprinkler, beat,
   blubber, boil, breakers, breeze, bubble, bubbles, butter,
   carbon tet, carbon tetrachloride, carbon-dioxide foam, carbonation,
   chaff, chalk, chip, churn, clay, cobweb, collar, cork, cream,
   cushion, deck gun, deluge set, dough, down, dribble, drivel,
   driven snow, drool, dust, effervescence, eiderdown, ether,
   expectoration, extinguisher, fairy, feather, feather bed, feathers,
   ferment, fire apparatus, fire engine, fire hose, fire hydrant,
   fireplug, fizz, fleece, floss, flour, flue, fluff,
   foam extinguisher, froth, fume, fuzz, gossamer, head,
   hook-and-ladder, ivory, kapok, ladder pipe, lather, lily, maggot,
   mantle, meringue, milk, mote, mousse, mouth-watering, offscum,
   paper, pearl, pillow, plash, plush, ptyalism, pudding, puff,
   pumper, putty, rubber, saliva, salivation, satin, scud, scum,
   sea foam, seethe, sheet, shower, sialagogue, silk, silver, simmer,
   slabber, slaver, slobber, slosh, snorkel, snow, soapsuds, soda,
   souffle, sparge, sparkle, spatter, spindrift, spit, spittle,
   splash, splatter, sponge, spoondrift, spray, sprinkle, sprinkler,
   sprinkler head, sprinkler system, spume, sputum, stew, stinging,
   stir, straw, sud, suds, super-pumper, surf, swan, swansdown, swash,
   thistledown, velvet, water, water cannon, wax, wet blanket, whip,
   whisk, white water, wool, yeast, zephyr



Easton's 1897 Bible Dictionary:

Foam
   (Hos. 10:7), the rendering of _ketseph_, which properly means
   twigs or splinters (as rendered in the LXX. and marg. R.V.). The
   expression in Hosea may therefore be read, "as a chip on the
   face of the water," denoting the helplessness of the piece of
   wood as compared with the irresistable current.