Word Origin & History
1839, Amer.Eng., poker term, perhaps from Du. 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."
1680s, from Du. blaf "flat, broad," apparently a North Sea nautical term for ships with flat vertical bows, later extended to landscape features.