Source : Webster's Revised Unabridged Dictionary (1913)

Actuary \Ac"tu*a*ry\, n.; pl. {Actuaries}. [L. actuarius
   copyist, clerk, fr. actus, p. p. of agere to do, act.]
   1. (Law) A registrar or clerk; -- used originally in courts
      of civil law jurisdiction, but in Europe used for a clerk
      or registrar generally.

   2. The computing official of an insurance company; one whose
      profession it is to calculate for insurance companies the
      risks and premiums for life, fire, and other insurances.