open secret

US /ˈoʊpən ˈsiːkrət/
UK /ˈoʊpən ˈsiːkrət/
"open secret" picture
1.

公开的秘密

a fact that is supposed to be secret but is actually known by many people

:
It's an open secret that they are planning to get married.
他们要结婚是公开的秘密
His affair with his assistant was an open secret in the office.
他与助理的恋情在办公室里是公开的秘密