adjectival noun

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun linguistics A noun that functions as an adjective
• noun In Japanese grammar, a specific part of speech, categorized in Japanese as 形容動詞 (keiyō dōshi). Some of these words can be used as regular nouns, and all can be used as adjectives when followed by the postfix な (na), in contrast to Japanese common adjectives, 形容詞 (keiyōshi).