WordNet (r) 3.0 (2006):

unfamiliarity
    n 1: unusualness as a consequence of not being well known [syn:
         unfamiliarity, strangeness] [ant: familiarity]

Moby Thesaurus II by Grady Ward, 1.0:

69 Moby Thesaurus words for "unfamiliarity":
   agnosticism, amateurishness, amateurism, blankmindedness,
   brand-newness, callowness, dewiness, disaccustomedness,
   empty-headedness, freshness, gloss of novelty, greenhornism,
   greenness, hiatus of learning, ignorance, ignorantism,
   ignorantness, immaturity, inanity, inexperience, innocence,
   intactness, know-nothingism, knowledge-gap, lack of information,
   lateness, maidenhood, mint condition, nescience, newbornness,
   newfangledness, newfangleness, newness, newness to, novelness,
   novelty, nowness, obscurantism, originality, presentness,
   pristineness, rawness, recency, recentness, simpleness, simplicity,
   strangeness, tabula rasa, unaccustomedness, unacquaintance,
   unacquaintedness, unawareness, uncommonness, unconversance,
   unexperiencedness, unfledgedness, unhabituatedness, unintelligence,
   unknowing, unknowingness, unpracticedness, unprofessionalism,
   unprofessionalness, unripeness, unusualness, unwontedness, vacuity,
   vacuousness, virginity