Step 1: Understanding the Concept:
An interjection is a word or phrase that expresses strong emotion or surprise. It is often grammatically independent from the rest of the sentence.
Step 2: Detailed Explanation:
The word "Wow!" expresses a feeling of sudden excitement, wonder, or admiration.
It is followed by an exclamation mark, which is a common characteristic of interjections.
It does not describe a noun (adjective), join clauses (conjunction), or modify an action (adverb).
Step 3: Final Answer:
The word "Wow!" is an Interjection. Therefore, option (1) is correct.