Diogenianus 8.17 (where the punctuation, not before but after tou= bi/ou. makes better sense).
The headword (for which see also sigma 941) is not in Greek the unquantified length that it is in English but the extent of a spread hand, between thumb and little finger, i.e. about nine inches; cf. alpha 518, gamma 367, delta 1434, kappa 369, kappa 1434, pi 63.