Which word means to prohibit, ostracize, banish, or outlaw?

The chosen word, "proscribe," means to officially forbid or prohibit something, often associated with banning or denouncing particular practices, behaviors, or individuals. This term is especially used in legal or formal contexts where an authority may define and declare certain actions as unacceptable or illegal, effectively ostracizing or banishing them from accepted norms or practices.

While some of the other choices carry connotations of similar actions, they do not encapsulate the full sense conveyed by "proscribe." For instance, "banish" refers specifically to the act of sending someone away or removing them from a place, but lacks the comprehensiveness of prohibiting an action or a set of behaviors. "Exile" also focuses on the act of expelling someone, often from their home country, which emphasizes the physical removal rather than a broader prohibition of actions or practices. Similarly, "condemn" relates to expressing disapproval or censure, which does not inherently imply an official ban or prohibition, but more a moral judgment.

Thus, "proscribe" is the most precise and encompassing term regarding prohibiting and ostracizing actions or behaviors on an official level, making it the correct choice.