bluff has 4 distinct synonyms spread across 3 of its 7 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. WordNet records no antonym for it — antonymy is a relation between word forms rather than concepts, so it is deliberately sparse.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
a high steep bank (usually formed by river erosion)
pretense that your position is stronger than it really is
“his bluff succeeded in getting him accepted”
the act of bluffing in poker; deception by a false show of confidence in the strength of your cards
1 of the 7 recorded senses carries no synonym, antonym or related term, so it is not shown above. Every sense, with its definition and examples, is on the full entry for bluff.
Synonyms, antonyms and the broader and narrower relations for bluff come from Princeton University’s WordNet. Full sources and licences.
frighten someone by pretending to be stronger than one really is