noun
antipope
Historical term for a person claiming to be pope in opposition to the canonically elected pope, especially during the Western Schism.
中世ヨーロッパでは、対立教皇が立てられることがあった。
In medieval Europe, antipopes were sometimes set up.
教皇 is the legitimate pope, while 対立教皇 is a rival claimant.
Compound of 対立 (opposition) and 教皇 (pope), directly translating the Western concept of antipope.