descriptive adequacy
In linguistics, the property of a grammar that correctly accounts for the linguistic competence of native speakers, as opposed to merely generating the correct set of sentences (observational adequacy) or capturing generalizations (explanatory adequacy).
Chomsky proposed descriptive adequacy as a criterion for evaluating grammars.
Observational adequacy: the grammar correctly describes the observed data. Descriptive adequacy goes further by capturing the native speaker's internalized knowledge.
Explanatory adequacy: the grammar explains how linguistic knowledge is acquired. It is a higher level of adequacy than descriptive adequacy.
Compound of 記述的 (descriptive) + 妥当性 (adequacy, validity). A calque from English 'descriptive adequacy', used in generative linguistics.