An open secret is a concept or idea that is "officially" secret or restricted in knowledge, but is actually widely known; or refers to something which is widely known to be true, but which none of the people most intimately concerned are willing to categorically acknowledge in public.
Famous quotes containing the words open and/or secret:
“It is open to question whether the highly individualized characters we find in Shakespeare are perhaps not detrimental to the dramatic effect. The human being disappears to the same degree as the individual emerges.”
—Franz Grillparzer (1791–1872)
“The secret of fortune is joy in our hands.”
—Ralph Waldo Emerson (1803–1882)