non-gradable

From non- +‎ gradable.

non-gradable (not comparable)

1. That cannot be graded.
2. (linguistics) (of an adjective) Describing a quality that cannot normally be varied because it is extreme (e.g. freezing), absolute (e.g. dead), or classification (e.g. nuclear).

   Synonyms: ungradable, incomparable, uncomparable

   Antonym: gradable

• gradable

non-gradable (plural non-gradables)

1. (linguistics) Any adjective that is not gradable.

• “non-gradable”, in Cambridge English Dictionary, Cambridge, Cambridgeshire: Cambridge University Press, 1999–present.
• “non-gradable”, in Oxford Learner's Dictionaries
• ungradable, nongradable, uncomparable at the Google Books Ngram Viewer.
• ungradable adjectives, nongradable adjectives, uncomparable adjectives at the Google Books Ngram Viewer.