APOS'TASY, noun [Gr. a defection, to depart.] 1. An abandonment of what one has professed; a total desertion, or departure from one's faith or religion. 2. The desertion from a party to which one has adhered. 3. Among physicians, the throwing off of exfoliated or fractured bone, or the various solution of disease. 4. An abscess.
Source: Webster's 1828 American Dictionary ↗ · public-domain · returned verbatim, no AI