an athlete who has earned a letter in a school sport
"After three years of playing varsity soccer, Marcus finally received his first blue and gold letterman jacket at graduation."
A student who has attained a specified level of participation in a sporting or other activity, and is awarded a cloth “letter” to be affixed to an item of clothing.
"After three years on the varsity soccer team, Marcus proudly wore his new letterman jacket at the homecoming parade."