unavoidable

adj

1. Impossible to avoid; bound to happen.

   “an unavoidable urge”

2. Not voidable; incapable of being made null or void.

   “A confirmation is allied to a release, being a conveyance of an estate or right in esse whereby a voidable estate is made unavoidable”

noun

1. Something that cannot be avoided.

   “Forty years before, I had thought this odour one of the necessities of life — one of the unavoidables at least[…]”