The phrase "acted the part" means to portray a character or role convincingly. Its antonyms are words that indicate the opposite, which can include "faked," "pretended," "dissembled," "dissimulated," "misrepresented," "dishonest," or "insincere." These words imply that someone is not truthful or is misleading others by presenting a false persona. It is important to act the part with honesty and integrity, as portraying oneself in a false light can lead to damaging consequences. When choosing antonyms for "acted the part," it is crucial to consider the context of the situation and the message being conveyed.