WordNet (r) 3.0 (2006):

check bit
    n 1: (computer science) a bit that is used in an error detection
         procedure in which a 0 or 1 is added to each group of bits
         so that it will have either an odd number of 1's or an even
         number of 1's; e.g., if the parity is odd then any group of
         bits that arrives with an even number of 1's must contain
         an error [syn: parity bit, parity, check bit]