Sustainable rhymes with:
unsustainable, unsustainable, unsustainable, attainable, obtainable, unattainable, unobtainable, unsustainable, anable, attainable, explainable, obtainable, trainable, unattainable, unexplainable, unobtainable, unsustainable
Sustainable sounds like:
stampfli, stampley, stanfill, stanphill, stempel, stemple, stumble