According to the NCAA, the term "redshirt" means an athlete is not participating in competition for an entire academic year, but wishes to retain a year of eligibility for competition.
A qualifying NCAA athlete who has met all academic requirements prior to entering college for her freshman year has four years of eligibility for competition, regardless of what academic year she may be a part of during competition.
For example, should an athlete redshirt her freshman year, she would have four years of competition eligibility from her sophomore year on. This particular athlete may be a sophomore academically, but for competition purposes will be referred to as a "redshirt freshman."
For an athlete to receive a standard redshirt, the NCAA requires that player not be involved in any competition for the year he is redshirted. Any amount of competition time, even 1 minute on a basketball court during a regular season game, for example, counts as a season of eligibility.
Redshirted athletes are allowed to travel, practice and even dress for competition for their team during their redshirt season, but the minute they step on the playing field, they lose their redshirt status and use a season of eligibility.
Medical Hardship Exemption
The NCAA allows a seriously injured athlete to extend her eligibility period through a medical hardship exemption, commonly referred to by media outlets as a "medical redshirt," though the NCAA does not use this terminology.
An athlete can qualify for this exemption if she has a documented, incapacitating injury or illness that occurred in the first half of the basketball season and the student-athlete has not participated in more than two contests or dates of competition or 20 percent of her team's scheduled contests, whichever number is greater.