Final answer:
A licensed real estate broker working under another's supervision is known as an associate broker. They hold a broker's license but are not operating independently. This role is distinct from a real estate salesperson, trustee, or broker partner.
Step-by-step explanation:
A licensed real estate broker who opts to work under the name and supervision of another licensed broker is referred to as an associate broker. An associate broker holds a broker's license but chooses to work under another broker's oversight. This is different from a real estate salesperson, who must work under a broker's supervision but does not hold a broker's license themselves. A trustee, in the context of real estate, is someone who holds property in trust for another. A broker partner typically refers to a co-owner of a brokerage firm, rather than an individual working under the supervision of another broker.