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:
“Through open doors, the dining-room declares
A larger loneliness of knives and glass
And silence laid like carpet.”
—Philip Larkin (1922–1986)
“Two girls discover
the secret of life
in a sudden line of
poetry.”
—Denise Levertov (b. 1923)