Unthinkable
WordNet
adjective
(1) Incapable of being conceived or considered
WiktionaryText
Adjective
- incapable of being believed; incredible
- inconceivable or unimaginable; extremely improbable in a way that goes against common sense
- Nothing is unthinkable, nothing impossible to the balanced person, provided it comes out of the needs of life and is dedicated to life's further development - Lewis Mumford