A medical red shirt is not an official NCAA term, but the term is used when a student-athlete is injured after participating in a limited amount of competition during a particular academic year and then qualifies for a Medical Hardship Waiver.
Medical Hardship Waiver
If a student-athlete suffers a season-ending injury or illness after competing in a limited amount of competition during a particular academic year, he/she may qualify for a medical hardship waiver which would allow him/her an additional season of competition during the five-year period of eligibility. To qualify for a medical hardship:
(a) the student-athletes injury or illness must occur in one of the four seasons of intercollegiate competition or subsequent to the first day of classes in the student-athletes senior year in high school;
(b) the injury or illness must occur prior to the completion of the first half of the playing season that concludes with the NCAA championship in that sport and must result in incapacity to compete for the remainder of that playing season; and
(c) the injury or illness must occur when the student-athlete has not participated in more than two contests/dates of competition or 20% of the institutions scheduled contests/dates of competition in his/her sport (whichever number is greater).