Definitions of bluff:

• noun:   the act of bluffing in poker; deception by a false show of confidence in the strength of your cards
• noun:   pretense that your position is stronger than it really is

  Example: "His bluff succeeded in getting him accepted"

• noun:   a high steep bank (usually formed by river erosion)
• verb:   frighten someone by pretending to be stronger than one really is
• verb:   deceive an opponent by a bold bet on an inferior hand with the result that the opponent withdraws a winning hand
• adjective:   bluntly direct and outspoken but good-natured

  Example: "A bluff but pleasant manner"

• adjective:   very steep; having a prominent and almost vertical front

  Example: "A bluff headland"