The Collaborative International Dictionary of English v.0.48:

Infertile \In*fer"tile\, a. [L. infertilis: cf. F. infertile.
   See In- not, and Fertile.]
   Not fertile; not productive; barren; sterile; unable to
   propagate its kind; as, an infertile soil; an infertile
   hybrid; -- of living things and of soil or land.
   [1913 Webster +PJC]

WordNet (r) 3.0 (2006):

infertile
    adj 1: incapable of reproducing; "an infertile couple" [syn:
           sterile, unfertile, infertile] [ant: fertile]