pounce1
Pronunciation: /paʊns/
verb
- (of an animal or bird of prey) spring or swoop suddenly so as to catch prey: as he watched, a mink pounced on the vole
- (of a person) spring forward suddenly so as to attack or seize someone or something: the gang pounced on him and knocked him to the ground
- notice and take swift advantage of a mistake or sign of weakness: the paper pounced on her admission that she is still a member of CND

Origin:
late Middle English (as a noun denoting a tool for stamping or punching): origin obscure, perhaps from puncheon1. The noun sense 'a bird's claw' arose in the late 15th century and gave rise to the verb (late 17th century)