Interjection /(?)/

In·ter·jec·tion

Interjection

n.
  1. The act of interjecting or throwing between; also, that which is interjected.
    The interjection of laughing.
  2. A word or form of speech thrown in to express emotion or feeling, as O! Alas! Ha ha! Begone! etc. Compare Exclamation. (Gram.)
    An interjection implies a meaning which it would require a whole grammatical sentence to expound, and it may be regarded as the rudiment of such a sentence. But it is a confusion of thought to rank it among the parts of speech.
    — Earle.
    How now! interjections? Why, then, some be of laughing, as, ah, ha, he!