\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.