The Collaborative International Dictionary of English v.0.48:

Beldam \Bel"dam\ Beldame \Bel"dame\, n. [Pref. bel-, denoting
   relationship + dame mother: cf. F. belledame fair lady, It.
   belladonna. See Belle, and Dame.]
   [1913 Webster]
   1. Grandmother; -- corresponding to belsire.
      [1913 Webster]

            To show the beldam daughters of her daughter.
                                                  --Shak.
      [1913 Webster]

   2. An old woman in general; especially, an ugly old woman; a
      hag.

   Syn: hag, beldam, witch, crone.
        [1913 Webster]

              Around the beldam all erect they hang. --Akenside.
        [1913 Webster]

WordNet (r) 3.0 (2006):

beldam
    n 1: an ugly evil-looking old woman [syn: hag, beldam,
         beldame, witch, crone]
    2: a woman of advanced age [syn: beldam, beldame]

Moby Thesaurus II by Grady Ward, 1.0:

91 Moby Thesaurus words for "beldam":
   Jezebel, Mafioso, Young Turk, bag, bat, battle-ax, beast, berserk,
   berserker, biddy, bitch, bitch-kitty, bomber, brute, cat,
   common scold, crone, dame, demon, devil, dowager, drab, dragon,
   fiend, fire-eater, firebrand, fishwife, frump, fury, gammer, goon,
   gorilla, grandam, grandmother, granny, grimalkin, gunsel, hag,
   hardnose, hell-raiser, hellcat, hellhag, hellhound, hellion,
   holy terror, hood, hoodlum, hothead, hotspur, incendiary, killer,
   mad dog, madcap, matriarch, matron, monster, mugger, old battle-ax,
   old dame, old girl, old granny, old lady, old trot, old wife,
   old woman, rapist, revolutionary, savage, scold, she-devil,
   she-wolf, shrew, siren, spitfire, termagant, terror, terrorist,
   tiger, tigress, tough, tough guy, trot, ugly customer, violent,
   virago, vixen, war-horse, wild beast, wildcat, witch, wolf