Source : Webster's Revised Unabridged Dictionary (1913)

Anaerobia \An*a`["e]r*o"bi*a\, Anaerobes \An*a"["e]r*obes\, n.
   pl. [NL. anaerobia; an-not + a["e]ro- + Gr.? life.]
   (Bacteriol.)
   Ana["e]robic bacteria. They are called facultative
   ana["e]robia when able to live either in the presence or
   absence of free oxygen; obligate, or obligatory, ana["e]robia
   when they thrive only in its absence.