Present participial adjective
A present participial adjective (/ˈpresənt ˈpɑ:(r)tɪsɪpɪəl ˈæʤəktɪv/), or -ing adjective is an adjective that is derived from a present participle of a verb, and is a type of -ing form (itself a type of verbal.
For example, the sentence “Grammar is exciting!" describes the excitement of grammar, and exciting is derived from the verb excite.
Modern grammar may gloss over the differences between a present participial adjective and present participle, which at best are minor.
Learners may confuse present participial adjectives with past participial adjectives, and say things like “I am boring" instead of “I am bored.”
“Cunning" is an example of an adjective was e originally derived in this way but the verb it was derived from has fallen out of use (e.g. we don’t say *"to cun"). There may be others.