Meaning of “partner” - Learner’s Dictionary

partner

noun [ C ] uk us /ˈpɑːtnər/
RELATIONSHIP

B1 someone that you are married to or having a sexual relationship with:

sexual partners
Are partners invited to the office dinner?
SPORTS/DANCING

A2 someone that you are dancing or playing a sport or game with

BUSINESS

B2 someone who owns a business with another person:

a junior/senior partner
He's a partner in a law firm.
COUNTRY

a country that has an agreement with another country:

a trading partner
Britain and its European partners

(Definition of “partner noun” from the Cambridge Learner’s Dictionary © Cambridge University Press)