Definition of “sink” - Learner’s Dictionary

sink

verb uk us /sɪŋk/ (past tense and past participle sank, also US sunk, past participle sunk)
WATER [ I, T ]

B1 to go down or make something go down below the surface of water and not come back up:

The Titanic sank after hitting an iceberg.
During the first wave of attacks, they sank three enemy ships.
SOFT SUBSTANCE [ I, T ]

B1 to go down, or make something go down, into something soft:

My feet keep sinking into the sand.
It sank its teeth into his arm.
MOVE DOWN [ I ]

B2 to move down slowly:

The sun sank below the horizon.

(Definition of “sink verb” from the Cambridge Learner's Dictionary © Cambridge University Press)