A rookie is a person new to an occupation, profession, or hobby. In sports, a rookie is a professional athlete in their first season (or year). In contrast with a veteran who has experience, a rookie is typically considered needing more training and learning, though they may bring a new outside expertise to a job. Etymology. The Oxford English Dictionary states that the origins are uncertain, but that perhaps it is a corruption of the word recruit.
https://en.wikipedia.org/wiki/Rookie