INTERJECTION

Definition: A part of the speech that can independent express the emotion or a reaction. Although a interjección can form a complete sentence (that is to say, expressing a thought with no need of a subject and a verb), one can often also be inserted within an sentence, separated generally by commas of the rest of the sentence.

Examples in Spanish:

Ouch! = ¡Ay!
Wow! = ¡Caramba!
Ugh! = ¡Puf!
Oops! = ¡Uy!
Splat! = ¡Plaf!