The Collaborative International Dictionary of English v.0.48:

Interject \In`ter*ject"\, v. t. [imp. & p. p. Interjected; p.
   pr. & vb. n. Interjecting.] [L. interjectus, p. p. of
   interjicere to interject; inter between + jac[e^]re to throw.
   See Jet a shooting forth.]
   To throw in between; to insert; to interpose. --Sir H.
   Wotton.
   [1913 Webster]