The term "big-time operator" refers to an individual who is highly skilled in business, often operating on a large scale. Antonyms for this term could include "small-time operator", which refers to an individual who operates on a smaller scale or lacks the experience and skill level to be considered a big-time operator. Another antonym could be "amateur" or "novice", describing someone who is new to the industry and lacks the expertise to be considered a big-time operator. Alternatively, "incompetent" and "ineffective" could also be antonyms for a big-time operator, describing someone who lacks both the skill and experience to succeed in their business endeavors.