a partner whose name as a member of a firm is not revealed to the public.
Is It Time For All Couples To Use The Term “Partner”?There are a lot of different words one could use to describe the person with whom they're in a romantic relationship. But, the one word that is most quickly redefining the way we talk about relationships is partner.
Compare silent partner.
Origin of secret partner
First recorded in 1905–10
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019