Here's what rhymes with unavoidable.

Consider these alternatives

inescapable / capable unfortunate / fortunate unnecessary / very unforeseen / seen avoidable / voidable unwise / size foreseeable / agreeable unjustified / side counterproductive / productive superfluous / thus illogical / logical irrelevant / relevant unpleasant / present inconceivable / feasible entail / male unintended / prevented inevitability / stability foregone / long unfathomable / fashionable implausible / plausible unpalatable / charitable imperative / relative implication / education