What does Ostracize mean in romeo and Juliet?

Shakespeare did not use the word ostracize so you must be thinking of someone else's Romeo and Juliet. Ostracize is a word meaning to banish, deriving from the ancient Greek custom in Athens where the citizens could vote (by writing on bits of broken pottery called ostrakoi, hence "ostracize") to banish one of the citizens from the city as a punishment. "Banish" is of course a word that Shakespeare actually did use in his play Romeo and Juliet.