apostasy Share definition Flag The action of abandoning a party or getting cured from the effect of a religion virus, or a similar kind of brainwashing. See also apostate My reason for apostasy is that i don't want to practice stupidity in the name of religion anymore!! apostasy by Nipi February 11, 2006 0 0 Get merch Get the apostasy mug. Buy Now — $32.95 See more merch