simple past tense and past participle of stuff

Full or packed (with some material or substance). / (cooking) Filled with seasoning. / (slang) Full after eating. / (Australia, New Zealand, informal) Very tired.

present participle of stuff

The matter used to stuff hollow objects such as pillows and saddles. / Any of many food items used to stuff another. / A mixture of oil and tallow used in softening and dressing leather. / Severe defeat

plural of stuffing

(idiomatic, informal) One who is pompous or self-important, especially one who is officious in a position of authority. / (usually hyphenated) Used attributively.

(UK, colloquial, dismissal, euphemistic) Used to tell somebody to go away or to leave one alone.

blocked; stuffy; congested / (Britain) In a terrible state; messed up.

simple past tense and past participle of stuff up

(US) A soft toy in the form of an animal. / An animal that has undergone taxidermy.