Definition of redshirt:
(n) :
(US, sports) A college athlete who spends a year not participating in official athletic activities, but does not lose his or her eligibility to participate in following years.
(v) :
(US, collegiate sports) 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.
(v) :
(US, collegiate sports) To take on a status wherein one will spend a year not participating in official athletic activities.
(n) :
(fiction, science fiction, fandom slang) An unimportant character introduced only to be killed in order to underscore the peril to the important characters; an expendable character.
(v) :
(US) To hold a child out of kindergarten for one year in the hope that the child will do better academically and socially.
(n) :
(US, military) A person responsible for loading and unloading weapons, artillery, and equipment from aircraft.