A unit of information equal to 4 bits or 1/2 byte. This unit is used in telecommunications, where data is frequently transmitted in quadbits. In other contexts, the same unit is called a tetrad, a nibble, or a hexit
Russ Rowlett (Director), How Many? A Dictionary of Units of Measurement, Center for Mathematics and Science Education University of North Carolina, USA 2005. http://www.unc.edu/~rowlett/units/dictA.html, (Unit of Meas and Covr Factors - Amer) {608}