This article is from the Polyamory FAQ, by email@example.com (H. Wilper) with numerous contributions by others.
(Glad you asked that. ;-) ) Polyamory means "loving more than
one". This love may be sexual, emotional, spiritual, or any
combination thereof, according to the desires and agreements of
the individuals involved, but you needn't wear yourself out
trying to figure out ways to fit fondness for apple pie, or
filial piety, or a passion for the Saint Paul Saints baseball
club into it. "Polyamorous" is also used as a descriptive term by
people who are open to more than one relationship even if they
are not currently involved in more than one. (Heck, some are
involved in less than one.) Some people think the definition is
a bit loose, but it's got to be fairly roomy to fit the wide
range of poly arrangements out there.