the GNU version of the Collaborative International Dictionary of English
adj. Insupportable; unendurable.
The Century Dictionary and Cyclopedia
Insupportable.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
adj. not able to be supported or defended
Word Usage
"What I call unsupportable is your assertion that “Medstory’s results on any medical query are far superior to anything delivered by any other engine.”"