"Put one over" is a slang term which means to deceive or trick someone. Some common antonyms for this phrase could be honesty, sincerity, and straightforwardness. Other antonyms could include trustworthiness, reliability, and loyalty. People who are honest and sincere in their dealings with others are unlikely to try to put one over on them. Conversely, those who are untrustworthy, unreliable, or disloyal may be more likely to attempt to deceive or trick others. In any case, it is always important to be vigilant and cautious when dealing with others, especially when it comes to important matters such as business, finance, and personal relationships.