Synonyms for Decease (same or very similar meaning)
WordNet sense 1 (the event of dying or departure from life):
death, expiryWordNet sense 2 (pass from physical life and lose all bodily attributes and functions necessary to sustain life):
choke, conk, croak, die, exit, expire, go, pass, perish, pass away, pop off, buy the farm, cash in one's chips, give-up the ghost, kick the bucket, snuff itFrom the ODE community, based on WordNetadd/edit