Rookie is a term for a person who is in their first year of play of their sport and has little or no professional experience. The term also has the more general meaning of anyone new to a profession, training or activity (e.g. rookie cop, rookie pilot, as a synonym for recruit), or occasionally to a freshman (especially in athletic teams).
The term rookie has been modified in some online communities and is often referred to as simply rook, as a synonym for newbie.
In some sports there are traditions in which rookies must do things or tricks are played on them. Some examples in baseball include players having to dress up in strange costumes, or getting hit in the face with a cream pie; a traditional rookie "hazing" procedure in American football involves taping players to a goalpost and dousing them with ice water, Gatorade, and other substances.
Generally, a safe definition of rookie card is any trading card manufactured prior to or during an athlete's rookie year. This can come in a variety of formats including packs, boxes, sets, magazines, and more.
In NASCAR, rookies are symbolized by a yellow stripe on the rear bumper of the car that is placed on both sides of the name or symbol of the manufacturer of the car.
To qualify as a rookie in Major League Baseball, a player has to have fewer than 130 at bats or 50 innings pitched in the majors, or 45 days on the active rosters of major league clubs (excluding time on the disabled list or any time after rosters are expanded on September 1st)
A common urban legend suggests that the term derives from the game of chess; the "rook" in chess is often the last piece to be introduced into gameplay. This would appear to be consistent with the definition of "rookie". However, there are no known citations that prove or disprove this explanation.