Fiduciary
Someone legally required to act in your best interest, put your interests ahead of their own and disclose any conflicts.
Registered investment advisers owe their clients a fiduciary duty that covers the whole relationship. Brokers follow the SEC's Regulation Best Interest, which requires them to act in your best interest when they make a recommendation.
A fiduciary duty does not promise good returns or protect you from losses. It is about how advice is given. Ask any adviser whether they act as a fiduciary at all times for every account, and get the answer in writing.