associate

A person united with another or others in an act, enterprise, or business; a partner.

Somebody with whom one works, coworker, colleague.

A companion; a comrade.

One that habitually accompanies or is associated with another; an attendant circumstance.

A member of an institution or society who is granted only partial status or privileges.

(algebra) One of a pair of elements of an integral domain (or a ring) such that the two elements are divisible by each other (or, equivalently, such that each one can be expressed as the product of the other with a unit).