Redshirt definition

. Derived from the red jersey commonly worn by a player meeting this definition in practice scrimmages against the regulars.

an athlete who spends a year not participating in official athletic activities, but does not lose his or her eligibility to participate in following years

to place an athlete in a status wherein the athlete will spend a year not participating in official athletic activities, but will not lose his or her eligibility to participate in following years.

The university decided to redshirt the freshman linebacker to give him an extra year to build up his bulk.
To hold a child out of kindergarten for one year in the hope that the child will do better academically and socially.

Parents who redshirt their 5-year-olds instead of enrolling them in kindergarten are a concern to some Nebraska educators who are trying to reverse the trend of holding children back until age 6 to start school. —"Some Educators Oppose Redshirting 5-Year-Olds," The Omaha World-Herald, March 1, 1985

. From the tendency of red-shirted ensigns in the original Star Trek television series to die prematurely.

an unimportant character introduced only to be killed in order to underscore the peril to the important characters; an expendable character.

Sensing danger, Captain Kirk decided to beam down to the surface with Spock, McCoy, and a couple of redshirts.