the GNU version of the Collaborative International Dictionary of English
adj. That may be confirmed.
The Century Dictionary and Cyclopedia
Capable of being confirmed, established, or ratified; that may be made more certain.
Corroboratory.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
adj. capable of being tested (verified or falsified) by experiment or observation
Word Usage
"The idea is quite different -- that one can disagree about the legitimacy and or scope of the case and still be confirmable, that is, within the mainstream."