What is Redshirting?

Redshirting definition and meaning on Dictionary terms:
the practice of keeping a high-school or college athlete out of varsity competition for one year to develop skills and extend eligibility. the practice of delaying a child from starting kindergarten for one year, believed by some parents to give the child academic, athletic, and social advantages: academic redshirting; Is redshirting common practice at your school?

the practice of quickly killing off a newly introduced character in a TV show or movie.