Source : Webster's Revised Unabridged Dictionary (1913)

Unfertile \Un*fer"tile\, a.
   Not fertile; infertile; barren. -- {Un*fer"tile*ness}, n.

Source : WordNet®

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