to displace part of the volume of a supporting substance or object and become totally or partially submerged or enveloped; fall or descend into or below the surface or to the bottom (often fol. by in or into )

The battleship sank within two hours. His foot sank in the mud. Her head sinks into the pillows.

to fall, drop, or descend gradually to a lower level

The river sank two feet during the dry spell.

to settle or fall gradually, as a heavy structure

The tower is slowly sinking.

to fall or collapse slowly from weakness, fatigue, distress, etc.

He gasped and sank to his knees.

to slope downward; dip

The field sinks toward the highway.

to go down toward or below the horizon

the sun sinks in the west.

to penetrate, permeate, or seep (usually fol. by in or into )

Wipe the oil off before it sinks into the wood.

to become engulfed or absorbed in or gradually to enter a state (usually fol. by in or into )

to sink into slumber.

to be or become deeply absorbed or involved in a mood or mental state (usually fol. by in or into )

sunk in thought. She sank into despair.

to pass or fall into some lower state, as of fortune, estimation, etc.; degenerate

to sink into poverty.

to decline or deteriorate in quality or worth.

to fail in physical strength or health.

to decrease in amount, extent, intensity, etc.

The temperature sank to 30? at noon.

to become lower in volume, tone, or pitch

Her voice sank to a whisper.

to enter or permeate the mind; become known or understood (usually fol. by in or into )

He said it four times before the words really sank in.

to become concave; become hollow, as the cheeks.

to drop or fall gradually into a lower position

He sank down on the bench.

to cause to become submerged or enveloped; force into or below the surface; cause to plunge in or down

The submarine sank the battleship. He sank his fist into the pillow.

to cause to fall, drop, or descend gradually.

to cause to penetrate

to sink an ax into a tree trunk.

to lower or depress the level of

They sank the roadway by five feet.

to bury, plant, or lay (a pipe, conduit, etc.) into or as if into the ground.

to dig, bore, or excavate (a hole, shaft, well, etc.).

to bring to a worse or lower state or status.

to bring to utter ruin or collapse

Drinking and gambling sank him completely.

to reduce in amount, extent, intensity, etc.

to lower in volume, tone, or pitch.

to suppress; ignore; omit.

to invest in the hope of making a profit or gaining some other return

He sank all his efforts into the business.

to lose (money) in an unfortunate investment, enterprise, etc.

Sports .

to throw, shoot, hit, or propel (a ball) so that it goes through or into the basket, hole, pocket, etc.

She sank the 10 ball into the side pocket.

to execute (a stroke or throw) so that the ball goes through or into the basket, hole, pocket, etc.

to sink a putt; to sink a free throw.

a basin or receptacle, as in a kitchen or laundry, usually connected with a water supply and drainage system, for washing dishes, clothing, etc.

a low-lying, poorly drained area where waters collect and sink into the ground or evaporate.

sinkhole ( def. 2 ) .

a place of vice or corruption.

a drain or sewer.

a device or place for disposing of energy within a system, as a power-consuming device in an electrical circuit or a condenser in a steam engine.

any pond or pit for sewage or waste, as a cesspool or a pool for industrial wastes.

any natural process by which contaminants are removed from the atmosphere. ?

sink one's teeth into

to bite deeply or vigorously.

to do or enter into with great enthusiasm, concentration, conviction, etc.

to sink my teeth into solving the problem.