D defs.my
Entry 2 senses Webster, 1913

Interjection

/ĭn'tər.jĕkʹshən/ · In·ter·jec·tion · IPA /ˌɪn.tɚˈd͡ʒɛk.ʃən/
01 n. The act of interjecting or throwing between; also, that which is interjected.
  1. 1.
    The act of interjecting or throwing between; also, that which is interjected.
    “The interjection of laughing.” Bacon.
  2. 2.
    A word or form of speech thrown in to express emotion or feeling, as O! Alas! Ha ha! Begone! etc. Compare Exclamation.(Gram.) See: 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.