Source : Webster's Revised Unabridged Dictionary (1913)

Asexual \A*sex"u*al\ (?; 135), a. [Pref. a- not + sexual.]
   (Biol.)
   Having no distinct sex; without sexual action; as, asexual
   reproduction. See {Fission} and {Gemmation}.

Source : WordNet®

asexual
     adj : not havning or involving sex; "an asexual spore"; "asexual
           reproduction" [syn: {nonsexual}] [ant: {sexual}]