An abstract noun is a word for something that can't be experienced by any of the five senses; it can't be seen, heard, smelled, tasted, or touched. An abstract noun is a word for something that can only be known, understood, learned, believed, or felt emotionally. Some examples of abstract nouns are: There are some nouns that can be either abstract or concrete depending on use. For example, there's the physical heart that is beating in your chest and the heart of the matter or a broken heart. Then there are the tricky ones, the ones that you really have to think about.