Definition of rookies:
(n) :
An athlete either new to the sport or to a team or in his/her first year of professional competition, especially said of baseball, basketball, hockey and American football players.
(n) :
A novice.
(n) :
An inexperienced recruit, especially in the police or armed forces.
(adj) :
Non-professional; amateur
(v) :
(intransitive) To be a rookie; to go through one's inexperienced learning period in a job, team, or organization.
(v) :
(transitive, chiefly sports) To haze one or more rookies as an initiation ritual.