Nonce

"Nonce" is a portmanteau of "number used once". It is a numerical value, found by a Bitcoin miner, which is necessary to generate a block. In Bitcoin mining, it is necessary to calculate a hash that is smaller than the difficulty target to generate a block. As the hash value is the same no matter how many times it is calculated, the nonce is used to change the value and search for a number which is lower than the difficulty.