sink 
(sĭngk)
(sĭngk)v. sank (săngk) or sunk (sŭngk), sunk, sink·ing, sinks
v.intr.
1.
a. To go below the surface of water or another liquid: We watched the leaky inner tube slowly sink.
b. To descend to the bottom of a body of water or other liquid: found the wreck where it had sunk.
2.
a. To fall or drop to a lower level, especially to go down slowly or in stages: The water in the lake sank several feet during the long, dry summer.
b. To subside or settle gradually: Cracks developed as the building sank.
3. To appear to move downward, as the sun or moon in setting.
4. To slope downward; incline: The road sinks as it approaches the stream.
5.
a. To fall or lower oneself slowly, as from weakness or fatigue: The exhausted runner sank to the ground.
b. To feel great disappointment or discouragement: Her heart sank within her.
6.
a. To pass into something; penetrate: The claws sank into the flesh of the prey.
b. To steep or soak: The wine has sunk into my shirt.
7. To pass into a specified condition: She sank into a deep sleep.
8.
a. To deteriorate in quality or condition: The patient is sinking fast. The family sank into a state of disgrace.
b. To diminish, as in value: Gold prices are sinking.
9. To become weaker, quieter, or less forceful: His voice sank to a whisper.
10. To make an impression; become felt or understood: The meaning finally sank in.
v.tr.
1. To cause to descend beneath the surface or to the bottom of a liquid: sink a ship.
2.
a. To cause to penetrate deeply: He sank his sword into the dragon's belly.
b. To force into the ground: sink a piling.
c. To dig or drill (a mine or well) in the earth.
d. To cause to drop or lower: sank the bucket into the well.
e. Sports To propel (a ball or shot) into a hole, basket, or pocket.
3. To cause to be engrossed: "Frank sank himself in another book" (Patricia Highsmith).
4.
a. To make weaker, quieter, or less forceful: She sank her voice when the manager walked by.
b. To reduce in quantity or worth: The bad news will sink markets around the world.
5. To debase the nature of; degrade: The scandal has sunk him in the eyes of many.
6. To bring to a low or ruined state; defeat or destroy: Loss of advertising sank the newspaper.
7. To suppress or hide: He sank his arrogance and apologized.
8. Informal To defeat, as in a game.
9. To invest or spend, often without getting a return or adequate value: I've sunk a lot of money into that car.
10. To pay off (a debt).
n.
Idioms: 1. A water basin fixed to a wall or floor and having a drainpipe and generally a piped supply of water.
2. A cesspool.
3. A sinkhole.
4. A natural or artificial means of absorbing or removing a substance or a form of energy from a system.
5. A place regarded as wicked and corrupt: That city is a sink of corruption.
sink (one's) teeth into Informal
To undertake an endeavor energetically: She sank her teeth into the challenging project.
sink or swim Informal
To fail or succeed without alternative.
[Middle English sinken, from Old English sincan.]
sinka·ble adj.