Wiktionary
binary digit
n. (context computing English) Either of the characters 0 or 1 used in the binary numeral system.
WordNet
binary digit
n. either 0 or 1 in binary notation
Usage examples of "binary digit".
The idea was to see if binary digit pairs might match nucleotide bases.
This way each finger is a binary digit, 1 or 0 (a bit in computer terms).
The measuring rod, the unit of information, is something called a bit (for binary digit).
Thus any sufficiently crisp question can be answered by a single binary digit-0 or 1, yes or no.