The word 'wow' is a prime example of onomatopoeia, born from a spontaneous human exclamation of strong emotion. It first appeared in written English in the early 16th century, likely Scots in origin, as an interjection of surprise, wonder, or pleasure. Its power lies in its direct imitation of a vocal reaction, making it a natural and universally understood expression. The verb sense, meaning to overwhelm with admiration, developed in the 20th century from this expressive foundation, capturing the act of eliciting such a vocal response.

This is a simplex word of imitative origin, functioning as an interjection and verb.