Real Dictionary

stuff
uncountable noun: You can use stuff to refer to things such as a substance, a collection of things, events, or ideas, or the contents of something in a general way without mentioning the thing itself by name.
verb: If you stuff a container or space with something, you fill it with something or with a quantity of things until it is full.
verb: If you stuff something somewhere, you push it there quickly and roughly.
verb: If you stuff yourself, you eat a lot of food.

stuff in American English
the material or substance out of which anything is or can be made; raw material
intransitive verb: to cram oneself with food; eat gluttonously; gorge
noun: the material of which anything is made
transitive verb: to fill (a receptacle), esp. by packing the contents closely together; cram full

stuff in British English
to pack or fill completely; cram
noun: the raw material or fabric of something