Instructor (noun)

1. A person who teaches or gives instruction in a particular subject or skill.
2. A teacher or trainer in a school, college, or other educational institution.
3. A person who gives practical training or teaches a particular skill.

Origin:

From old french instruire "to teach, train" from latin instruere "to build, equip, furnish" from in- "in" + struere "to pile up".

Examples:

1. The instructor taught us how to use the equipment.
2. He is an instructor in mathematics.
3. The instructor was very knowledgeable.
4. The instructor was very patient with the students.
5. She is an instructor in swimming.