spilt milk
unbreakable
nonbreakable
inseparable
unavoidable
fact of life
unchangeable
immutable
unerasably
unpreventable
unextinguishably
unchewable
unspoilably
forbidden fruit
nonrecyclable
unquenchably
you can't unring a bell
hanger
unsaleable
unsalable
nonthreat
impossible
unundoable
possibilium
keepable
bound to
cannot
unappeasably
get out of jail free card
ineliminably
possible
supporter
ensnarement
inextinguishably
unslakeable
life buoy
indispensability
unshatterable
inerasable
unpindownable
unemptiable
undiminishably
imperishable
underailable
nonnegotiable
nonreturnable
discardable
unmitigably
essential
nonreversibly