The Collaborative International Dictionary of English v.0.48:

Proclivity \Pro*cliv"i*ty\, n. [L. proclivitas: cf. F.
   proclivit['e].]
   [1913 Webster]
   1. Inclination; propensity; proneness; tendency. "A
      proclivity to steal." --Abp. Bramhall.
      [1913 Webster]

   2. Readiness; facility; aptitude.
      [1913 Webster]

            He had such a dexterous proclivity as his teachers
            were fain to restrain his forwardness. --Sir H.
                                                  Wotton.
      [1913 Webster]

WordNet (r) 3.0 (2006):

proclivity
    n 1: a natural inclination; "he has a proclivity for
         exaggeration" [syn: proclivity, propensity, leaning]