1911 Encyclopædia Britannica/Bluff

BLUFF (a word of uncertain origin; possibly connected with an obsolete Dutch word, blaf, broad), an adjective used of a ship, meaning broad and nearly vertical in the bows; similarly, of a cliff or shore, presenting a bold and nearly perpendicular front; of a person, good-natured and frank, with a rough or abrupt manner. Another word “bluff,” perhaps connected with German verblüffen, to baffle, meant originally a horse’s blinker, the corresponding verb meaning to blindfold; it survives as a term in such games as poker, where “to bluff” means to bet heavily on a hand so as to make an opponent believe it to be stronger than it is; hence such phrases as “the game of bluff,” “a policy of bluff.”