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.
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   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]