Englishill-founded
adjective
your faith in his expertise was ill-founded:
baseless, groundless, without foundation, foundationless, without basis, unjustified, unsupported;
unsubstantiated, unproven, unverified, uncorroborated, unconfirmed, unauthenticated, not backed up by evidence, speculative, conjectural;
unsound, unreliable, questionable, misinformed, misguided, spurious, trumped-up.
▷antonyms well founded.
ill-founded Oxford Dictionary of English