The Collaborative International Dictionary of English v.0.48:

Virago \Vi*ra"go\ (?; 277), n.; pl. Viragoes. [L. virago,
   -intis, from vir a man. See Virile.]
   1. A woman of extraordinary stature, strength, and courage; a
      woman who has the robust body and masculine mind of a man;
      a female warrior.
      [1913 Webster]

            To arms! to arms! the fierce virago cries. --Pope.
      [1913 Webster]

   2. Hence, a mannish woman; a bold, turbulent woman; a
      termagant; a vixen.
      [1913 Webster]

            Virago . . . serpent under femininity. --Chaucer.
      [1913 Webster]

WordNet (r) 3.0 (2006):

virago
    n 1: a noisy or scolding or domineering woman
    2: a large strong and aggressive woman [syn: amazon, virago]

Moby Thesaurus II by Grady Ward, 1.0:

78 Moby Thesaurus words for "virago":
   Jezebel, Mafioso, Xanthippe, Young Turk, amazon, androgyne,
   battle-ax, beast, beldam, berserk, berserker, bitch, bitch-kitty,
   bomber, brute, butch, cat, common scold, demon, devil, dragon,
   dyke, fiend, fire-eater, firebrand, fishwife, fury, goon, gorilla,
   grimalkin, gunsel, hag, hardnose, harpy, hell-raiser, hellcat,
   hellhag, hellhound, hellion, holy terror, hood, hoodlum, hothead,
   hotspur, hoyden, incendiary, killer, lesbian, mad dog, madcap,
   monster, mugger, ogress, rapist, revolutionary, romp, savage,
   scold, she-devil, she-wolf, shrew, siren, spitfire, termagant,
   terror, terrorist, tiger, tigress, tomboy, tough, tough guy,
   ugly customer, violent, vixen, wild beast, wildcat, witch, wolf