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.
© Webster 1913.