Definify.com
Webster 1913 Edition
Antipope
An′ti-pope
,Noun.
One who is elected, or claims to be, pope in opposition to the pope canonically chosen; esp. applied to those popes who resided at Avignon during the Great Schism.
Webster 1828 Edition
Antipope
AN'TIPOPE
,Noun.
One who usurps the papal power, in opposition to the pope.
AN'TIPOPE
,Noun.