unthinkable
unt·hin·kable
adjective
1.
incapable of being conceived or considered
Origin
From un- + think + -able.
Related words
See also
WordNet 2.1 (Princeton University). Wiktionary (CC BY-SA). CMU Pronouncing Dictionary. WordNet 2.1 Copyright Princeton University. All rights reserved. Wiktionary content is available under the Creative Commons Attribution-ShareAlike Licence.