1. (a.) Not founded; not built or established.

2. (a.) Having no foundation; baseless; vain; idle; as, unfounded expectations.

Barmecidal Barmecide airy apparent apparitional autistic baseless bottomless chimeric contrary to fact deceptive delusional delusionary delusive delusory dereistic dishonest dreamlike dreamy empty erroneous fallacious FALSE fantastic garbled gratuitous groundless idle ill-founded illusional illusionary illusive illusory imaginary in error inauthentic inconclusive indecisive mendacious miscited misleading misquoted misreported misstated not following not proved not true ostensible phantasmagoric phantasmal phantom seeming self-deceptive self-deluding specious spectral spurious supposititious truthless unactual unascertained unattested unauthentic unauthenticated unauthoritative unbased uncalled-for uncertified unconfirmed uncorroborated undemonstrated undetermined unestablished unfixed ungrounded unjustifiable unjustified unproved unproven unreal unreliable unsettled unshown unsound unsubstantial unsubstantiated unsupportable unsupported unsupported by evidence unsustainable unsustained untenable untested untried untrue untruthful unvalidated unverified unwarranted vain visionary without basis without foundation without grounds