The Collaborative International Dictionary of English v.0.48:

Seethe \Seethe\, v. t. [imp. Seethed(Sod, obs.); p. p.
   Seethed, Sodden; p. pr. & vb. n. Seething.] [OE.
   sethen, AS. se['o]?an; akin to D. sieden, OHG. siodan, G.
   sieden, Icel. sj??a, Sw. sjuda, Dan. syde, Goth. saubs a
   burnt offering. Cf. Sod, n., Sodden, Suds.]
   To decoct or prepare for food in hot liquid; to boil; as, to
   seethe flesh. [Written also seeth.]
   [1913 Webster]

         Set on the great pot, and seethe pottage for the sons
         of the prophets.                         --2 Kings iv.
                                                  38.
   [1913 Webster]

WordNet (r) 3.0 (2006):

seething
    adj 1: in constant agitation; "a seething flag-waving crowd
           filled the streets"; "a seething mass of maggots";
           "lovers and madmen have such seething brains"-
           Shakespeare