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 related to open secret:
“GOETHE, raised o’er joy and strife,
Drew the firm lines of Fate and Life,
And brought Olympian wisdom down
To court and mar, to gown and town,
Stooping, his finger wrote in clay
The open secret of to-day.”
—Ralph Waldo Emerson (1803–1882)