The Collaborative International Dictionary of English v.0.48:

Amativeness \Am"a*tive*ness\, n. (Phren.)
   The faculty supposed to influence sexual desire; propensity
   to love. --Combe.
   [1913 Webster]

WordNet (r) 3.0 (2006):

amativeness
    n 1: the arousal of feelings of sexual desire [syn:
         amorousness, eroticism, erotism, sexiness,
         amativeness]