The Collaborative International Dictionary of English v.0.48:

Vixen \Vix"en\, n. [AS. fixen a she-fox, for fyxen, fem. of fox.
   See Fox.]
   1. A female fox. [Obs. or Prov. Eng.]
      [1913 Webster]

   2. A cross, ill-tempered person; -- formerly used of either
      sex, now only of a woman. --Barrow.
      [1913 Webster]

            She was a vixen when she went to school. --Shak.
      [1913 Webster]

WordNet (r) 3.0 (2006):

vixen
    n 1: a malicious woman with a fierce temper [syn: vixen,
         harpy, hellcat]
    2: a female fox

Moby Thesaurus II by Grady Ward, 1.0:

97 Moby Thesaurus words for "vixen":
   Jezebel, Mafioso, Partlet, Xanthippe, Young Turk, amazon,
   battle-ax, beast, beldam, berserk, berserker, biddy, bitch,
   bitch-kitty, bomber, bossy, brood mare, brute, cat, common scold,
   cow, demon, devil, doe, dragon, ewe, ewe lamb, fiend, filly,
   fire-eater, firebrand, fishwife, fury, goon, gorilla, grimalkin,
   guinea hen, gunsel, gyp, hag, hardnose, harpy, heifer, hell-raiser,
   hellcat, hellhag, hellhound, hellion, hen, hind, holy terror, hood,
   hoodlum, hothead, hotspur, incendiary, jenny, killer, lioness,
   mad dog, madcap, mare, monster, mugger, nanny, nanny goat, ogress,
   peahen, rapist, revolutionary, roe, savage, scold, she-bear,
   she-devil, she-goat, she-lion, she-wolf, shrew, siren, slut, sow,
   spitfire, termagant, terror, terrorist, tiger, tigress, tough,
   tough guy, ugly customer, violent, virago, wild beast, wildcat,
   witch, wolf