a descent as through liquid (especially through water) | plumbing fixture consisting of a water basin fixed to a wall or floor and having a drainpipe |
a slow fall or decline (as for lack of strength) | a covered cistern; waste water and sewage flow into it |
a feeling caused by uneasiness or apprehension | a depression in the ground communicating with a subterranean passage (especially in limestone) and formed by solution or by collapse of a cavern roof |
| (technology) a process that acts to absorb or remove energy or a substance from a system |