Green’s Dictionary of Slang

1. (UK Und.) a swindler.

a.1790

H.T. Potter New Dict. Cant (1795) n.p.: bluffer [...] an impudent saucy fellow.

2. one who relies on an assumed manner to get away with lies.

1910		‘O. Henry’ ‘The Call of the Tame’ in Strictly Business (1915) 106: If I hadn’t seen you once bluff three bluffers from Mazatzal City with an empty gun.
1920		Marvel 14 Aug. 3: He felt sure that he was a bluffer – that he had not the contempt for money he presumed to have.