a person whose occupation is teaching
"The swimming instructor helped me improve my stroke technique during our morning practice session."
One who instructs; a teacher.
"The swimming instructor adjusted my arm position to help me glide through the water more efficiently."
In plain English: An instructor is someone who teaches you how to do something.
"The swimming instructor taught me how to float on my back."
Usage: Use instructor to describe someone who teaches or trains others in a specific subject, skill, or activity. Unlike a general teacher found in schools, an instructor often leads specialized courses, workshops, or military training sessions.
The word comes from the Latin instructor, which was formed by adding a suffix meaning "one who does an action" to the verb instruct. It originally referred to someone who trains or teaches others and traveled into English with that same core meaning of providing instruction.