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:
“Speech and silence. We feel safer with a madman who talks than with one who cannot open his mouth.”
—E.M. Cioran (b. 1911)
“And do not pity C. Q. One had to choose between him and H. H., and one wanted H. H. to exist at least a couple of months longer, so as to have him make you live in the minds of later generations. I am thinking of aurochs and angels, the secret of durable pigments, prophetic sonnets, the refuge of art. And this is the only immortality you and I may share, my Lolita.”
—Vladimir Nabokov (1899–1977)