yes, it is. because this theory divides the english parts of speech into eight parts: noun, pronoun, adjective, preposition, adverb, conjunction,and inerjection. this theory hasproduced important indispensable grammatical concepts such as subject, object, predicate, subject complement, object complement, and many others.
Well, what I heard from a book called Blood On The River, the American Indians made it up. It said that "wow" means wonder and awe.The online etymological dictionary credits it to a Scottish inerjection meaning wonder & awe, circa 1513.