A set of definitions exists in the Senate ESEA bill written and voted out of the HELP Committee (Health, Education, Labor and Pensions).
Reps and sets are terms used by exercise professionals, athletes and individuals in the gym. They provide structure and organization to your workout. If you work with a personal trainer or physical therapist, she will prescribe an exercise based on a specific number of sets and reps.
Sets and repetitions are fundamental weight training concepts to understand thoroughly. When you perform a specific exercise, you typically repeat a specific action a certain number of times, or reps. Reps is short for repetitions. The number of repetitions you perform before you stop is a set.