The Collaborative International Dictionary of English v.0.48:

Ogre \O"gre\ ([=o]"g[~e]r), n. [F., fr. Sp. ogro, fr. L. Orcus
   the god of the infernal regions; also, the lower world,
   hell.]
   An imaginary monster, or hideous giant of fairy tales, who
   lived on human beings; hence, any frightful giant; a cruel
   monster.
   [1913 Webster]

         His schoolroom must have resembled an ogre's den.
                                                  --Maccaulay.
   [1913 Webster]

WordNet (r) 3.0 (2006):

ogre
    n 1: a cruel wicked and inhuman person [syn: monster, fiend,
         devil, demon, ogre]
    2: (folklore) a giant who likes to eat human beings

Moby Thesaurus II by Grady Ward, 1.0:

76 Moby Thesaurus words for "ogre":
   Argus, Briareus, Cerberus, Charybdis, Cyclops, Dracula, Echidna,
   Frankenstein, Gorgon, Harpy, Hydra, Loch Ness monster, Medusa,
   Minotaur, Pegasus, Python, Scylla, Sphinx, Talos, Typhon, Wolf-man,
   bogey, bogeyman, brute, bugaboo, bugbear, cad, centaur, chimera,
   cockatrice, demon, dragon, drake, fee-faw-fum, fiend, frightener,
   ghost, ghoul, giant, griffin, hippocampus, hobgoblin, holy terror,
   horror, incubus, man-eater, mermaid, merman, monster, nightmare,
   nixie, ogress, phantom, revenant, roc, sadist, salamander, satyr,
   scarebabe, scarecrow, scarer, scoundrel, sea horse, sea serpent,
   siren, specter, succubus, terror, troll, unicorn, vampire, villain,
   werewolf, windigo, xiphopagus, zombie