1sink 
/ˈsɪŋk/ verb
sinks; sank /ˈsɪŋk/ verb /ˈsæŋk/ or sunk /ˈsʌŋk/; sunk sink·ing 1 a [no obj] : to go down below the surface of water, mud, etc.
▪ The passengers were rescued from the boat before it sank. ▪ a sinking ship ▪ The rock sank to the bottom of the pool. ▪ My foot sank into the deep mud. ▪ She sank up to her knees in the snow.
b [+ obj] : to cause (a ship or boat) to go down below the surface of water
▪ The torpedo sank the ship. 2 [no obj] : to move down to a lower position
▪ The sun sank behind the hills. ▪ He sank to his knees and prayed. [=he knelt down and prayed] ▪ She sank back into the cozy chair. 3 [no obj] : to become lower in amount, value, etc. : to decline or decrease
▪ The temperature sinks quickly after the sun sets. ▪ The lake's water level is slowly sinking. ▪ His strength is slowly sinking. ▪ The company's stock sank after it announced that profits were less than expected. ▪ The currency's value is sinking. 4 [+ obj] : to use force to cause (something) to go into the ground or another surface — often + into ▪ He sank [=drove] the fence posts into the ground. ▪ He sank the ax into the tree. ▪ The nail was sunk all the way into the wall. ▪ The cat sank its claws into my arm. 5 [no obj] a : to do something that is morally wrong
▪ How could you sink [=stoop] to cheating? ▪ I never thought he could sink so low. [=do something so wrong]
b : to begin to feel sad, depressed, etc.
▪ She sank into a deep depression. ▪ Her heart sank [=she became very sad] at the thought of moving so far away. ▪ With a sinking heart [=with great sadness], she signed the papers to sell the house. ▪ She got that sinking feeling [=a feeling of dread or discouragement] as she viewed the storm damage.
c : to go or change to a worse or less active state — often + into ▪ The patient sank into a coma. ▪ He's sinking fast and won't live much longer. 6 [no obj] of a person's voice : to become quieter
▪ Her voice sank to a whisper. [=she began to whisper] 7 a [no obj] : to become less successful : to move toward failure
▪ The company is sinking under the weight of heavy debt. [=the company is failing because it has too much debt]
b [+ obj] : to cause (someone or something) to fail
▪ Bad weather sank their plans for a picnic. ▪ If we don't get that money soon, we'll be sunk. 8 [+ obj] : to make (a well, shaft, mine, etc.) by digging down into the earth
▪ The workers are sinking a well. 9 [+ obj] : to spend (a lot of money, work, time, etc.) on something — + in or into ▪ He sank [=invested] five million dollars in the new company. ▪ He keeps sinking money into that old car. ▪ She has sunk a lot of work into the project. 10 [+ obj] : to throw, hit, or roll (a ball) into a hole or basket
▪ He sank [=dropped, holed] the putt. ▪ In pool, you need to sink [=pocket] the eight ball to win. ▪ She sank the jump shot. 11 [+ obj] chiefly Brit, informal : to drink (something) completely
▪ They sank [=downed] one more pint before leaving.
▪ The passengers were rescued from the boat before it sank. ▪ a sinking ship ▪ The rock sank to the bottom of the pool. ▪ My foot sank into the deep mud. ▪ She sank up to her knees in the snow.
b [+ obj] : to cause (a ship or boat) to go down below the surface of water
▪ The torpedo sank the ship.
▪ The sun sank behind the hills. ▪ He sank to his knees and prayed. [=he knelt down and prayed] ▪ She sank back into the cozy chair.
▪ The temperature sinks quickly after the sun sets. ▪ The lake's water level is slowly sinking. ▪ His strength is slowly sinking. ▪ The company's stock sank after it announced that profits were less than expected. ▪ The currency's value is sinking.
▪ How could you sink [=stoop] to cheating? ▪ I never thought he could sink so low. [=do something so wrong]
b : to begin to feel sad, depressed, etc.
▪ She sank into a deep depression. ▪ Her heart sank [=she became very sad] at the thought of moving so far away. ▪ With a sinking heart [=with great sadness], she signed the papers to sell the house. ▪ She got that sinking feeling [=a feeling of dread or discouragement] as she viewed the storm damage.
c : to go or change to a worse or less active state — often + into ▪ The patient sank into a coma. ▪ He's sinking fast and won't live much longer.
▪ Her voice sank to a whisper. [=she began to whisper]
▪ The company is sinking under the weight of heavy debt. [=the company is failing because it has too much debt]
b [+ obj] : to cause (someone or something) to fail
▪ Bad weather sank their plans for a picnic. ▪ If we don't get that money soon, we'll be sunk.
▪ The workers are sinking a well.
▪ He sank [=dropped, holed] the putt. ▪ In pool, you need to sink [=pocket] the eight ball to win. ▪ She sank the jump shot.
▪ They sank [=downed] one more pint before leaving.
sink in [phrasal verb]
: to become completely known, felt, or understood
▪ I had to tell him what to do over and over before it finally sank in. ▪ The fact that she's left me still hasn't really sunk in.
▪ I had to tell him what to do over and over before it finally sank in. ▪ The fact that she's left me still hasn't really sunk in.
sink like a stone
: to sink very suddenly and quickly
▪ The ship hit an iceberg and sank like a stone. — often used figuratively ▪ His last movie sank like a stone.
▪ The ship hit an iceberg and sank like a stone. — often used figuratively ▪ His last movie sank like a stone.
sink or swim
◊A situation in which you either sink or swim is one in which you must succeed by your own efforts or fail completely.
▪ They left me to sink or swim on my own. ▪ In this job, it's sink or swim.
▪ They left me to sink or swim on my own. ▪ In this job, it's sink or swim.
sink without a trace (US) or Brit sink without trace
: to sink beneath the water to a place that cannot be seen or found
▪ The boat sank without a trace. — often used figuratively ▪ Her first album was a big success, but after that she sank without a trace.
▪ The boat sank without a trace. — often used figuratively ▪ Her first album was a big success, but after that she sank without a trace.
sink your teeth into — see tooth
