a. [ Cf. F. sexagésimal. ] Pertaining to, or founded on, the number sixty. [ 1913 Webster ]

Sexagesimal fractions or
Sexagesimal numbers (Arith. & Alg.), those fractions whose denominators are some power of sixty; as, 1/60, 1/3600, 1/216000; -- called also astronomical fractions, because formerly there were no others used in astronomical calculations. --
Sexagesimal arithmetic, or
Sexagenary arithmetic, the method of computing by the sexagenary scale, or by sixties. --
Sexagesimal scale (Math.), the sexagenary scale. [ 1913 Webster ]

n. A sexagesimal fraction. [ 1913 Webster ]