1. The abandonment of a faith or of principles once professed; desertion of one's party.

Nuttall's Standard dictionary of the English language By Nuttall, P.Austin

• aposticy,
• apostacy,
• apostals,
• zpostasy,
• spostasy,
• wpostasy,
• qpostasy,
• aoostasy,
• appostasy,
• aposatasy,
• apotasy,
• epostasy,
• arctostapylos,
• isoostasy,
• amyostasi,
• apostasiz,
• apostass,
• episytasy,
• epystasy,
• apastasy

• apostle,
• apostate,
• apostleship,
• apostatise,
• apostatize.

The adjective form of "apostasy" is "apostate".

The plural of the "apostasy" can be the "apostasies".

The singular of the "apostasy" can be the "apostasy".