bluff (v.) Look up bluff at Dictionary.com
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.
bluff (n.1) Look up bluff at Dictionary.com
"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.
bluff (n.2) Look up bluff at Dictionary.com
1844 as an alternative name for poker; from bluff (v.). As "an act of bluffing" by 1864.