Webster's Revised Unabridged Dictionary · 1913

Sexagenary

Sexagenary , adjective

[Latin sexagenarius, from sexageni sixty each, akin to sexaginta sixty, sex six: compare sexagénaire. See Six.]

Pertaining to, or designating, the number sixty; poceeding by sixties; sixty years old.
Collocations (2)
Sexagenary arithmetic , See under Sexagesimal.
Sexagenary scale or Sexagesimal scale (Mathematics) , a scale of numbers in which the modulus is sixty. It is used in treating the divisions of the circle.

Sexagenary , noun

1.
Something composed of sixty parts or divisions.
2.
A sexagenarian. — Sir W. Scott