Rookie is a term (mainly in North American usage) for a person who is in their first year of play of their sport and has little or no professional experience.
In North America, 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).
Rookies (in the sporting sense) can be submitted to hazing as a pledge in some clubs.
The term rookie has been modified in some online communities and is often referred to as simply rook, which means noob or newbie.
In most 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.
The Oxford English Dictionary states that the origins are uncertain, but that perhaps it is a corruption of the word recruit. The earliest example from the OED is from Rudyard Kipling's Barrack-Room Ballads (published 1892): So 'ark an' 'eed, you rookies, which is always grumblin' sore, referring to rookies in the sense of raw recruits to the British Army.