Synonyms for Pass away:

n.

breathe your last (breath), lay down your life, starve, lose your life, drown. pass away (noun)
decease, exit, expire, pass, die, perish, go.

v.

die (verb)
die, pass, perish, pass on, fall, decease, expire, succumb, part, depart.
end (verb)
die, decease, wrap up, finalize, stop, halt, conclude, expire, end, finish, checkmate, complete, accomplish, cease, close, cap, pass on, terminate, exit, culminate.

Other synonyms:

starve. drown. Other relevant words:
go.