su·per·vi·sor 
(spər-vī′zər)
(spər-vī′zər)n.
1. One who supervises.
2. One who is in charge of a particular department or unit, as in a governmental agency or school system.
3. One who is an elected administrative officer in certain US counties and townships.
su′per·viso·ry (-vīzə-rē) adj.