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

Moby Thesaurus II by Grady Ward, 1.0:

148 Moby Thesaurus words for "seething":
   agitation, ardent, baking, blistering, bluster, bobbery, boil,
   boiling, boiling over, brewing, broiling, brouhaha, burning,
   burning hot, burning with excitement, bustle, canicular, churn,
   coction, commotion, conturbation, decoction, discomposure,
   disorder, disquiet, disquietude, disturbance, drench, drenching,
   ducking, dunking, ebullience, ebulliency, ebullient, ebulliometer,
   ebullition, embroilment, excitement, febrile, ferment,
   fermentation, fervent, fervid, fever, feverish, feverishness,
   fidgets, fiery, flaming, flap, flurry, flushed, fluster,
   flutteration, foment, fume, fuss, glowing, grilling, heated,
   hectic, het up, hot, hot as fire, hot as hell, hubbub, hurly-burly,
   imbruement, imbuement, impregnation, in rut, infiltration,
   infusion, injection, inquietude, jitters, jumpiness, leaching,
   like a furnace, like an oven, lixiviation, maceration, maelstrom,
   malaise, moil, nerviness, nervosity, nervousness, overheated,
   overwarm, parching, passionate, percolation, permeation,
   perturbation, piping hot, pulping, red-hot, restlessness, roasting,
   roil, rout, row, saturation, scalding, scorching, searing, seethe,
   sexually excited, simmer, simmering, sizzling, sizzling hot,
   smoking hot, smoldering, soak, soakage, soaking, sopping, souse,
   sousing, steaming, steamy, steeping, stewing, stir, sudorific,
   sweating, sweaty, sweltering, sweltry, swirl, to-do, toasting,
   torrid, trepidation, trepidity, tumult, tumultuation, turbidity,
   turbulence, turmoil, twitter, unease, unrest, upset, warm,
   white-hot