Definition of "bluff"

BLUFF OR POKER [title of a chapter]

1845, Hoyle's Games

Situated on bluffs above the Huangpu, a tributary of the Yangtze, Shanghai—which means ‘above the sea’—is sinking.

2020, David Farrier, “Thin Cities”, in Footprints, 4th Estate

a bluff or bold shore

1769, William Falconer, "Côte en écore" (entry in An Universal Dictionary of the Marine)

Its banks, if not really steep, had a bluff and precipitous aspect.

1845, Sylvester Judd, Margaret: A Tale of the Real and the Ideal, Blight and Bloom; Including Sketches of a Place Not Before Described, Called Mons Christi

[…] he had a bluff, rough-and-ready face, all roughened and reddened and lined in his long travels.

1881–1882, Robert Louis Stevenson, Treasure Island, London, Paris: Cassell & Company, published 14 November 1883

There is indeed a bluff pertinacity which is a proper defence in a moment of surprise.

1832, [Isaac Taylor], Saturday Evening. […], London: Holdsworth and Ball

Not a sparrow on the cottage thatch, where the chimney's warmth had thawed the snow, that did not seem to have his great coat on, so bluffed out were the feathers, and not a frozen-out duck who did not glance up at the icicles hanging to the roof, and quack a prayer for rain.

1866, Grantley F[itzhardinge] Berkeley, “Incidents of Sport”, in My Life and Recollections. [...] Complete in Four Volumes, volume III, London: Hurst and Blackett, publishers, successors to Henry Colburn, […], page 124

[W]hen the bare boughs of a tree intervened between her and the rising bright but deep red sun, frosted as the twigs were, on them sat a merry flock of sparrows, the feathers on their breasts bluffed out, as if they had donned warm winter spencers to shield them from the biting blast.

1870, Grantley F[itzhardinge] Berkeley, “The Fair Doe of Fernditch”, in Tales of Life and Death. [...] In Two Volumes, volume I, London: Chapman and Hall, […], page 117

I remember one idle bright afternoon here when Phillip bluffed out his little chest, sneaking expectant glances back at me and Cammy, until she "restrained" him from bickering with that beagle.

2002, Nick Fowler, “Sunday in the Park with Sores”, in A Thing (or Two) about Curtis and Camilla, New York, N.Y.: Pantheon Books; 1st Vintage Contemporaries edition, New York, N.Y.: Vintage Books, June 2003, pages 285–286