decease

curtains, death, demise, dissolution, doom, end, exit, expiration, expiry, fate, grave, great divide, passage, passing, quietus, sleep

check out, conk (out), croak [slang], demise, depart, die, drop, end, exit, expire, fall, flatline, go, kick in [slang], kick off [slang], part, pass (on), pass away, peg out [chiefly British], perish, pop off, step out, succumb