I did some learning this weekend. I had heard about Red Shirt, but I did not know about "Gray Shirt" offers. 

A grayshirt is a college freshman who starts school in the winter instead of the fall. They don't enroll full-time at first and only take part-time classes without joining the team or getting a scholarship. The NCAA gives you five years to play four years of sports; eligibility starts when they go full-time. Might be slightly different for NAIA. Still reading.