The term 'call one's bluff' is a phrase used to describe a situation in which someone challenges another person to prove that they are telling the truth. The two crossword solutions for this term are 'DARE' (4 letters) and 'uptheante' (9 letters). 'DARE' is a verb meaning to challenge someone to do something, while 'uptheante' is an idiom meaning to increase the stakes or risks of a situation. Together, these two words capture the essence of the phrase 'call one's bluff, ' which is to challenge someone to prove their truthfulness by increasing the stakes.