ETYM Latin, a preparer: cf. French instructeur.
1. One who instructs; one who imparts knowledge to another; a teacher.
2. A rank beneath assistant professor, at a university; an adjunct professor.

1. One that trains
2. One (as a machine or vehicle) used in training
3. A person who treats the ailments and minor injuries of the members of an athletic team
4. One who trains other persons or animals.