Source : Webster's Revised Unabridged Dictionary (1913)

Sexagenary \Sex*ag"e*na*ry\, a. [L. sexagenarius, fr. sexageni
   sixty each, akin to sexaginta sixty, sex six: cf.
   sexag['e]naire. See {Six}.]
   Pertaining to, or designating, the number sixty; poceeding by
   sixties; sixty years old.

   {Sexagenary arithmetic}. See under {Sexagesimal}.

   {Sexagenary}, or {Sexagesimal}, {scale} (Math.), a scale of
      numbers in which the modulus is sixty. It is used in
      treating the divisions of the circle.