The state of having rejected your religious beliefs or your political party or a cause (often in favor of opposing beliefs or causes)

The act of abandoning a party for cause

Apostasy in Islam is commonly defined as the abandonment of Islam by a Muslim, in thought, word, or through deed.

The terms Apostasia or Iouliana or the Royal Coup are used to describe the political crisis in Greece centered on the resignation, on 15 July 1965, of Prime Minister Georgios Papandreou and subsequent appointment, by King Constantine II, of successive prime ministers from Papandreou's own party, the Centre Union, to replace him.

Apostasy is a Swedish black metal band formed in 2000.

Apostasy is a 1948 Japanese drama film directed by Keisuke Kinoshita, based on the novel The Broken Commandment by Tōson Shimazaki.

Apostasy is a 2017 British drama film about Jehovah's Witnesses directed by Daniel Kokotajlo.