The Collaborative International Dictionary of English v.0.48:

Quirky \Quirk"y\ (kw[~e]rk"[y^]), a.
   Full of quirks; tricky; as, a quirky lawyer.
   [1913 Webster]

WordNet (r) 3.0 (2006):

quirky
    adj 1: informal terms; strikingly unconventional [syn: far-
           out, kinky, offbeat, quirky, way-out]