unthinkable

/ˈʌnˌθɪŋkəbəl/

/ənˈθɪŋkəbəl/

Definitions of unthinkable

1. adjective

   incapable of being conceived or considered
   synonyms:

   incredible, unbelievable

   beyond belief or understanding

   impossible

   not capable of occurring or being accomplished or dealt with

   impossible, inconceivable, out of the question, unimaginable

   totally unlikely

   antonyms:

   thinkable

   capable of being conceived or imagined or considered

   believable, credible

   capable of being believed

   possible

   capable of happening or existing

   cogitable, ponderable

   capable of being thought about

   conceivable, imaginable

   capable of being imagined

   presumable, supposable, surmisable

   capable of being inferred on slight grounds