shark /ʃɑːk $ ʃɑːrk/ noun [countable]
[Sense 1: Date: 1400-1500; Origin: Origin unknown. ]
[Sense 2: Date: 1500-1600; Origin: Probably from German schurke 'bad man'; influenced by ⇒ shark(1)]

1. a large sea fish with several rows of very sharp teeth that is considered to be dangerous to humans:
Sharks were circling around our boat.
shark-infested waters (=waters where there are a lot of sharks)

2. informal someone who cheats other people out of money
pool/card shark (=someone who uses their skill at pool or cards to cheat other players out of money)
⇒ loan shark

[TahlilGaran] Dictionary of Contemporary English ▲

shark
noun
ADJ. killer, man-eating
SHARK + VERB attack sb, maul sb
SHARK + NOUN attack | fishing
PHRASES shark-infested The boat went down in shark-infested waters off the coast of South Africa.

[TahlilGaran] Collocations Dictionary ▲