Tedious is the adjective from tedium, which is both Latin and English for boredom. You ordinarily wouldn't use tedious for people, just things; you might say "His speeches are tedious," but usually not "He is tedious." Something that is tedious could also be called tiresome.

Is tedious a noun or verb?

The noun tedium comes from the Latin root word taedere, meaning "to weary of," and that's still what tedium means today: bored and weary of it all. The noun can also mean a tedious period of time — school concerts and assemblies are always two hours of tedium. Tedious is a related adjective form of the word.

Can tedious be an adverb?

In a tedious or wearisome manner.