In United States college athletics, redshirt is a delay or suspension of an athlete's participation in order to lengthen his or her period of eligibility. Typically, a student's athletic eligibility in a given sport is four seasons, a number derived from the four years of academic classes that are normally required to obtain a bachelor's degree at an American college or university. However, a student athlete may be offered the opportunity to redshirt for up to two years, which allows the athlete to spread those four years of eligibility over five, or sometimes six years. In a redshirt year, a student athlete may attend classes at the college or university, practice with an athletic team, and dress for play but he or she may not compete during the game. Using this mechanism, a student athlete has up to five academic years to use the four years of eligibility, thus becoming a fifth-year senior.
The term is used as a verb, noun, and adjective. For example, a coach may choose to redshirt a player who is then referred to as a redshirt freshman or simply a redshirt.