Meaning of “stuff” - Learner’s Dictionary

stuff

verb [ T ] uk us /stʌf/
stuff sth in/into/behind, etc

to push something into a small space, often quickly or in a careless way:

He stuffed the papers into his briefcase and left.
FILL

to completely fill a container with something:

an envelope stuffed with money
FOOD

to fill meat, vegetables, etc with a mixture of food before you cook them:

stuffed peppers
DEAD ANIMAL

to fill the body of a dead animal with special material so that it looks as if it is still alive

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