An adjectival noun is a word that is used in a context wherein it combines the functions of two parts of speech. The term may be used to describe three such situations:

• a noun that functions as an adjective, especially in Japanese grammar (see Adjectival noun (Japanese));
• a noun that functions as an adjective can be called an adjectival noun in English (e.g. Fowler), but it is nowadays more often called a noun adjunct or attributive noun;
• an adjective that functions as a noun, e.g. the other, the True, the rich and the poor, especially in German and other inflected languages (see adjectival noun (noun)).