The term "bigtime operator" refers to a person who is a master at what they do, often in a powerful or successful position. Antonyms, on the other hand, are words that have the opposite meaning of another word. For "bigtime operator," some antonyms could be novice, amateur, rookie or beginner. These words suggest inexperience or lack of knowledge in the respective area. Other antonyms could include underachiever, failure or loser, which imply a lack of success or underperformance. It is important to consider the context in which these words are used to choose the most appropriate antonym.