in petto

[…] it was not unfrequent for a good bargain to be struck with him by one or more of the public functionaries, the difference between the sum proposed and accepted being settled against the interests of Mynheer Krause, by the party putting him in possession of some government movement which hitherto been kept in petto.

1837, Capt. Marryat, “Snarleyyow; or, the Dog Fiend”, in The Metropolitan magazine, volume 18, page 18

[…] in its nine members, stand prominently personified indolence and ignorance consummate, solemn pedantry and petulance in petto, upstart self-conceit and high-born arrogance all-blustering, self-sufficiency all smirking, and solid acres in all their stolidity, the remnant of vigour on crutches, and of saintly talent ever dozing—all this is indeed prophetic of wo to the land.

1838, “War in Disguise”, in Blackwood's Edinburgh magazine, volume 44, number 278, page 718

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 October 26, Max Beerbohm, Zuleika Dobson, or, An Oxford Love Story, 1st American edition, New York, N.Y.: John Lane Company, published 1912, →OCLC

And yet, thou brave Teufelsdröckh, who could tell what lurked in thee? […] The secrets of man’s Life were laid open to thee; thou sawest into the mystery of the Universe, farther than another; thou hadst in petto thy remarkable Volume on Clothes.

1831, Thomas Carlyle, “Reminiscences”, in Sartor Resartus: The Life and Opinions of Herr Teufelsdröckh. […], London: Chapman and Hall, […], →OCLC, 1st book, page 10

In the same department as the suspect allographic prefaces we will naturally put many a “Notice from the Publisher [or Editor],” […] which we will meet again and which we have every reason to attribute in petto (but only in petto) to the author.

1997, Gérard Genette, Paratext: Thresholds of Interpretation, →ISBN, page 190