v.intr. 1 cease from agitation; become tranquil; abate (excitement subsided). 2 (of water, suspended matter, etc.) sink. 3 (of the ground) cave in; sink. 4 (of a building, ship, etc.) sink lower in the ground or water. 5 (of a swelling etc.) become less. 6 usu. joc. (of a person) sink into a sitting, kneeling, or lying posture. subsidence n.
[ L subsidere (as SUB-, sidere settle rel. to sedere sit) ]