Insession
Insession , noun
[Latin insessio, from insidere, insessum, to sit in. See Insidious.]
1.
The act of sitting, as in a tub or bath. [Rare]
Used by way of fomentation, insession, or bath.
2.
That in which one sits, as a bathing tub. [Rare]
Insessions be bathing tubs half full.