This is the 14704th most frequent Polish word.
pustego
"Empty."
The word "pustego" is used as an adjective describing the state of the carton (masculine form), indicating that it is empty.
Musiałem wyrzucić pustego kartonu po soku.
I had to throw away the empty juice carton.
Here, "pustego" is used in an idiomatic expression referring to an empty stomach (neuter form).
Nie miałem siły do życia na pustego.
I didn't have the strength to live on an empty stomach.
In this sentence, "pustego" is applied to the room (masculine form), describing its lack of occupants or furniture as an adjective.