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:
“I rarely speak about God. To God, yes. I protest against Him. I shout at Him. But to open a discourse about the qualities of God, about the problems that God imposes, theodicy, no. And yet He is there, in silence, in filigree.”
—Elie Wiesel (b. 1928)
“The secret of ugliness consists not in irregularity, but in being uninteresting.”
—Ralph Waldo Emerson (1803–1882)