The definition of the word: Klazomaniac
Klazomaniac is a noun.
Klazo is a Greek word that means ‘to scream’. Klazomania refers to compulsive shouting, like in the disorder Tourette syndrome. It is a real condition but not much is known about it.
A klazomaniac is a person WHO CAN ONLY SPEAK BY SHOUTING. ALL CAPS = SHOUTING as you well know!