English

Adjective

unascertainable ‎(comparative more unascertainable, superlative most unascertainable)

1. That cannot be ascertained; uncertain, unable to be determined or discovered.
   • 1946, Bertrand Russell, History of Western Philosophy, I.19:

     Everything one would wish to know of the relations of Aristotle and Alexander is unascertainable, the more so as legends were soon invented on the subject.

Antonyms

• ascertainable