Is the word not always an adverb?

The negative Word "not" is practically always an adverb, modifying adjectives (e.g. not large) or adverbs (e.g. not completely). But it can be used with linking verbs to indicate a negative state (e.g. He is not a hero) and has been adopted in logic programming to be a noun (a NOTis an operator that returns an inverse state: false if the operand is true, true if the operand is false).