Meaning of “thrash” - Learner’s Dictionary

thrash

verb uk us /θræʃ/
HIT [ T ]

to hit a person or animal several times as a punishment

MOVE [ I ]

to move from side to side in a violent way:

He was screaming in pain and thrashing around on the floor.
DEFEAT [ T ] informal

to win against someone very easily

(Definition of “thrash” from the Cambridge Learner’s Dictionary © Cambridge University Press)