adj. That cannot be proved or verified by any test
The Century Dictionary and Cyclopedia
Not capable of being proved, demonstrated, confirmed, or established. Also spelled unproveable.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
adj. not provable
Word Usage
"Don't give me this load about degineration if you are going to make assertions such as, the * "unprovable" aspects of an open agenda, and expect no reply."