Date: Wed Nov 8 00:40:54 EST 1995
Subject: A.Word.A.Day--facultative

fac.ul.ta.tive \'fak-*l-.ta-t-iv\ aj 1a: of or relating to the grant of
permission, authority, or privilege 1b: OPTIONAL 2: of or relating to a
mental faculty 3a: having opposite reactions under different conditions 3b:
able to live or thrive under more than one set of conditions - av

In bacteriology, some organisms that are ordinarily aerobic
(growing in air) may be facultative anaerobes (able to survive without oxygen).