uncommunicable

But Bernard Levin, writing in The London Observer that same year, noted that “as a communication of the uncommunicable, ‘Conundrum’ is very good indeed.”

But they made no sound and what I had almost remembered was uncommunicable forever.

The word 'prig' is untranslatable and uncommunicable.

Mr. Byrd, who had such solid, if private and uncommunicable, reasons for believing in the guilt of Craik Mansell, was somewhat taken aback at this unlooked-for decision of Mr. Ferris, and, remembering the temptation which a man like Hickory must feel to make his cause good at all hazards, cast a sharp look toward that blunt-spoken detective, in some doubt as to whether he could be relied upon to keep his promise in the face of this manifest disappointment.

Humboldt is inclined to believe that the possibility of such a method of ascertaining longitude was that uncommunicable secret, which Sebastian Cabot many years later hinted at on his death-bed.