Answer : Knowledge is the noun form of knowledge. This noun belongs to the class of abstract nouns. An abstract noun can be described as a noun that relates to a quality Idea or state rather than being a specific fixed object. Abstract nouns are generally related to immaterialistic or abstract items.
The word abstract itself means something that is related to the things with which we cannot physically interact, but these are things that are quality or general ideas. The word knowledge is an abstract noun because it does not relate to an object, but it is in general a term which is related to the intelligent quotient of a person.