grader

Short definition from Wiktionary

Noun

1. 1
   A machine used in road maintenance, construction, and mining for leveling large surfaces.
2. 2
   A machine used to sort food by size or quality.
3. 3
   One who grades, or that by means of which grading is done or facilitated.
4. 4
   One who belongs to a certain grade at school.

Proper noun

1. 1
   A surname.