Antonyms of adj challengeable

1 sense of challengeable

Sense 1
challengeable -- (capable of being challenged)

INDIRECT (VIA contestable) -> incontestable, incontestible -- (incapable of being contested or disputed)

Similarity of adj challengeable

1 sense of challengeable

Sense 1
challengeable -- (capable of being challenged)
       => contestable (vs. incontestable) -- (capable of being contested)