Source : Webster's Revised Unabridged Dictionary (1913)

Anaerobic \An*a`["e]*rob"ic\, a. [Pref. an-not + a["e]robic.]
   (Biol.)
   Not requiring air or oxygen for life; -- applied especially
   to those microbes to which free oxygen is unnecessary;
   ana["e]robiotic; -- opposed to {a["e]robic}.

Anaerobic \An*a`["e]*rob"ic\, a. (Biol.)
   Relating to, or like, ana["e]robies; ana["e]robiotic.

Source : WordNet®

anaerobic
     adj 1: living or active in the absence of free oxygen; "anaerobic
            bacteria" [syn: {anaerobiotic}] [ant: {aerobic}]
     2: not aerobic; "isometric exercises are anaerobic" [ant: {aerobic}]