When it comes to nouns, there are two major categories:
Category 1: Proper versus Common
Category 2: Concrete versus Abstract
The word hour is a common noun and an abstract noun.
You classify concrete and abstract nouns by their ability to register on your five senses. If you can see, hear, smell, taste, or feel the item, it's a concrete noun. If, however, you cannot experience the item with any of your senses, it's abstract. Read more here ...
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