in petto adjective 2adverb 1 adjective2 •Secret, private.The boudoir that would be yours is a blue room. Four Watteaus hang in it. In the dining-hall hang portraits of my forefathers—in petto, your forefathers-in-law—by many masters. — 1911 •Designated as a cardinal but not yet announced.In future you will have the right to dress in red — indeed, you are already cardinal in petto, and you will be proclaimed at the next conclave. — 1845 adverb1 •Privately, in secret.Ministers and their Majority had a rejoinder in petto, as we have explained above; but it was one which they could not for shame avow, though they voted on the strength of it. — 1834
