1839, American English, poker term, perhaps from Dutch bluffen "to brag, boast," or verbluffen "to baffle, mislead." An identical word meant "blindfold, hoodwink" in 1670s, but the sense evolution and connection are unclear; OED calls it "one of the numerous cant terms ... which arose between the Restoration and the reign of Queen Anne." Extended or figurative sense by 1854. Related: Bluffed; bluffing.
"broad, vertical cliff," 1680s, from bluff (adj.) "with a broad, flat front" (1620s), a sailors' word, probably from Dutch blaf "flat, broad." Apparently a North Sea nautical term for ships with flat vertical bows, later extended to landscape features.
1844 as an alternative name for poker; from bluff (v.). As "an act of bluffing" by 1864.
To force someone to justify or validate a pretense; require the truth: When she called his bluff, he had to admit he was lying (1870s+)
: His courage was all bluff •A noun sense fr 1849 is ''an excuse'' (1870s+)
To use confident pretense as a means of winning or succeeding •The 1674 definition is ''to blindfold or hoodwink''; the game of poker was originally known as bluff (1670s+)
[perhaps related to, though not derived fr, a late 1700s bluff, ''a blindfold or blinker for a horse'']