unhintable

comparative more unhintable · superlative most unhintable

1. That must not be hinted at; unmentionable.

   The whole visit was tense with Soppy's unhintable doings.

   2015, Peter Dickinson, Skeleton-in-Waiting

   1 more example

   With the word 'baby' unmentionable and unhintable, we all had to go on pretending that my mother was in bed for some slight cold, or other indisposition.

   1955, John Wyndham, The Chrysalids