Here's what rhymes with penetrable.
impenetrable Words that almost rhyme with penetrable
eligible equitable heritable educable pensionable inevitable creditable demonstrable estimable reputable revocable predicable intelligible negligible irrevocable inequitable inheritable questionable objectionable disreputable discreditable impressionable pestilential unmentionable unintelligible exceptionable unquestionable unobjectionable unexceptionable