What are Abstract Nouns. Abstract nouns are words that name things that are not concrete. Your five physical senses cannot detect an abstract noun â you canât see it, smell it, taste it, hear it, or touch it. In essence, an abstract noun is a quality, a concept, an idea, or maybe even an event. Abstract nouns and concrete nouns are usually defined in terms of one another. Something that is abstract exists only in the mind, while something that is concrete can be interacted with in a physical way.