Interjection
Pronunciation : In`ter*jec"tion
Part of Speech : n.
Etymology : [L. interjectio: cf. F. interjection. See Interject.]
Definition : 1. The act of interjecting or throwing between; also, that which is interjected. The interjection of laughing. Bacon.
2. (Gram.)
Defn: A word or form of speech thrown in to express emotion or feeling, as O! Alas! Ha ha! Begone! etc. Compare Exclamation. 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! Shak.
Source : Webster's Unabridged Dictionary, 1913