What is "insession"

Insession \In*ses"sion\, n. [L. insessio, fr. insidere, insessum, to sit in. See Insidious.]

1. The act of sitting, as in a tub or bath. ``Used by way of fomentation, insession, or bath.'' [R.]
   --Holland.

2. That in which one sits, as a bathing tub. [R.]

   Insessions be bathing tubs half full.
   --Holland.

n. 1 The act of sitting, as in a tub or bath. 2 That in which one sits, as a bathing tub.