Antonyms of adj improvable

1 sense of improvable

Sense 1
improvable -- (susceptible of improvement)

INDIRECT (VIA corrigible) -> incorrigible -- (impervious to correction by punishment)

Similarity of adj improvable

1 sense of improvable

Sense 1
improvable -- (susceptible of improvement)
       => corrigible (vs. incorrigible) -- (capable of being corrected or set right; "a corrigible defect"; "a corrigible prisoner")