The Collaborative International Dictionary of English v.0.48:

Injoint \In*joint\, v. t. [Pref. in- in + joint.]
   To join; to unite. [R.] --Shak.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Injoint \In*joint\, v. t. [Pref. in- in + joint.]
   To disjoint; to separate. [Obs.] --Holland.
   [1913 Webster]