The Collaborative International Dictionary of English v.0.48:

oddity \odd"i*ty\ ([o^]d"[i^]*t[y^]), n.; pl. Oddities
   ([o^]d"[i^]*t[i^]z).
   1. The quality or state of being odd; singularity; queerness;
      peculiarity; as, oddity of dress, manners, and the like.
      [1913 Webster]

            That infinitude of oddities in him.   --Sterne.
      [1913 Webster]

   2. That which is odd; as, a collection of oddities.
      [1913 Webster]

WordNet (r) 3.0 (2006):

oddity
    n 1: eccentricity that is not easily explained [syn: oddity,
         oddness]
    2: a strange attitude or habit [syn: oddity, queerness,
       quirk, quirkiness, crotchet]
    3: something unusual -- perhaps worthy of collecting [syn:
       curio, curiosity, oddity, oddment, peculiarity,
       rarity]

Moby Thesaurus II by Grady Ward, 1.0:

116 Moby Thesaurus words for "oddity":
   aberration, abnormality, absurdity, alien, anomalousness, anomaly,
   anticness, bizarreness, bizarrerie, card, case, character, conceit,
   conversation piece, crackpot, crackpotism, crank, crankiness,
   crankism, crotchet, crotchetiness, curio, curiosity, curiousness,
   deformity, deviancy, deviation, differentness, distinctiveness,
   divergence, dottiness, duck, eccentric, eccentricity, erraticism,
   erraticness, exception, extraordinariness, fanatic, fantasticality,
   freak, freakiness, freakishness, grotesqueness, grotesquerie,
   hermit, hobo, idiocrasy, idiosyncrasy, improbability, incongruity,
   incongruousness, individuality, irregularity, kink, kook,
   kookiness, lone wolf, loner, maggot, malformation, mannerism,
   maverick, meshuggenah, misfit, monstrosity, monstrousness,
   museum piece, natural, nonconformist, nonconformity, nonesuch, nut,
   odd fellow, oddball, oddness, original, outlandishness, outsider,
   pariah, peculiarity, phenomenon, prodigiosity, prodigy, quaintness,
   queer duck, queer fish, queer specimen, queerness, quip, quirk,
   quirkiness, quiz, rara avis, rarity, screwball, singularity,
   solitary, spook, strange thing, strangeness, teratism, tramp,
   trick, twist, type, unconventionality, unnaturalness, unusualness,
   weirdness, weirdo, whim, whimsicality, whimsy, zealot, zombie