Third person singular present tense of apostatize: to abandon one's religious faith, political party, or principles.
From Late Latin apostatizare, derived from Greek apostasia (standing away from), from apo- (away) + stasis (standing). The term evolved from religious contexts describing those who renounced their faith to broader meanings of abandoning any set of beliefs.
The word apostasy shaped entire medieval legal systems—apostates were sometimes executed or had their property seized, which created intense documentation of their trials; we know more about some medieval apostates' personal doubts than about ordinary believers because their 'standing away' was so heavily recorded.
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