A teacher is a person who teaches.
A teacher is a person who teaches something.
A teacher is a person who teaches something to someone.
A teacher is a person who teaches something to somebody.
Link to teaching page
A pilot is a person who flies a plane, a helicopter or some other flying vehicle.
An engineer is a person who designs and maintains engines and systems.
A physicist is a person who works in the field of physics.
A salesman is a person who sells things for a living.
The Problem of Definitions
The map is not the territory. it is difficult to find a definition which accurately describes a thing completely. This is a limitation of language. Words point to things but do not replace them or exist in totality as them.
A man who sells his own things is not a salesman…