An abstract noun is a noun that refers to an idea, emotion, feeling, or quality that cannot be detected by the five senses (touch, taste, hearing, sight, smell), compared with a concrete noun.

In many Indo-European languages the majority of abstract nouns are of feminine gender. Many abstract nouns are formed by adding noun-forming suffixes to adjectives, such as -ness and -ity in English, e.g. happiness, serenity. Other examples of abstract nouns in English include: beauty, bravery, deceit, history, size.