definitional (adj.)

late 14c., diffinicioun, definicion, "decision, setting of boundaries, determination and stating of the limits and distinctive nature of a thing," also "limitations," also "a statement of the meaning of a word or phrase," from Old French definicion, from Latin definitionem (nominative definitio) "a bounding, a boundary; a limiting, prescribing; a definition, explanation," the last sense most often in Cicero, noun of action from past-participle stem of definire "to limit, determine, explain," from de "completely" (see de-) + finire "to bound, limit," from finis "boundary, end" (see finish (v.)). In logic, meaning "act of stating what something means" is from 1640s. Meaning "degree of distinctness of the details in a picture" is from 1889.

suffix forming adjectives from nouns or other adjectives, "of, like, related to, pertaining to," Middle English -al, -el, from French or directly from Latin -alis (see -al (2)).