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 am pretty sure that, if you will be quite honest, you will admit that a good rousing sneeze, one that tears open your collar and throws your hair into your eyes, is really one of life’s sensational pleasures.”
—Robert Benchley (1889–1945)
“The secret of the illusoriness is in the necessity of a succession of moods or objects. Gladly we would anchor, but the anchorage is quicksand.”
—Ralph Waldo Emerson (1803–1882)