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:
“O polished perturbation! golden care!
That keep’st the ports of slumber open wide
To many a watchful night.”
—William Shakespeare (1564–1616)
“That is the whole secret of successful fighting. Get your enemy at a disadvantage; and never, on any account, fight him on equal terms.”
—George Bernard Shaw (1856–1950)