verifiable
Much of what we think we know about the universe is unverifiable.
She made various unverifiable claims about the private lives of local officials.
Most of the claims in the report are unsubstantiated and unverifiable.
The newspaper explored the allegations about the president and found that they were unverifiable.

SMART Vocabulary: related words and phrases

True, real, false, and unreal
actual
actuality
actually
all that glitters is not goldidiom
alternate reality
false
false flag
falsely
fantastical
fever dream
non-realistic
not so muchidiom
nothing could be further from the truthidiom
nothing could have been further from my mind/thoughtsidiom
parallel universe
unproven
unreal
untrue
untruly
urban myth