disclusion

noun3

1. •
   A separation of the teeth when the jaw is slightly opened.
2. •
   Especially, a separation of posterior teeth when the lower jaw moves forward, as a natural result of the alignment of the anterior teeth.
3. •
   (no longer used) A shutting off; exclusion.

   • impressed in the Brain, the composition of them, and disclusion and various disposal of them, is plainly an arbitrarious act, — 1659