The noun sink has 4 senses (first 1 from tagged texts)
1. (4) sink -- (plumbing fixture consisting of a water basin fixed to a wall or floor and having a drainpipe)
2. sink -- ((technology) a process that acts to absorb or remove energy or a substance from a system; "the ocean is a sink for carbon dioxide")
3. sinkhole, sink, swallow hole -- (a depression in the ground communicating with a subterranean passage (especially in limestone) and formed by solution or by collapse of a cavern roof)
4. cesspool, cesspit, sink, sump -- (a covered cistern; waste water and sewage flow into it)
Overview of verb sink
The verb sink has 9 senses (first 9 from tagged texts)
1. (8) sink, drop, drop down -- (fall or drop to a lower place or level; "He sank to his knees")
2. (5) sink -- (cause to sink; "The Japanese sank American ships in Pearl Harbor")
3. (4) sink, pass, lapse -- (pass into a specified state or condition; "He sank into Nirvana")
4. (3) sink, settle, go down, go under -- (go under, "The raft sank and its occupants drowned")
5. (3) sink, subside -- (descend into or as if into some soft substance or place; "He sank into bed"; "She subsided into the chair")
6. (2) dip, sink -- (appear to move downward; "The sun dipped below the horizon"; "The setting sun sank below the tree line")
7. (2) slump, fall off, sink -- (fall heavily or suddenly; decline markedly; "The real estate market fell off")
8. (1) slump, slide down, sink -- (fall or sink heavily; "He slumped onto the couch"; "My spirits sank")
9. (1) bury, sink -- (embed deeply; "She sank her fingers into the soft sand"; "He buried his head in her lap")