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.
Reps is short for repetitions. Repetitions defines the number of times to perform an exercise. For example, you do 12 squats, then stop. The 12 squats you perform are considered 12 repetitions. If you curl the dumbbell 15 times, then you have completed 15 repetitions of biceps curls.