Plural: actuaries

ETYM Latin actuarius copyist, clerk, from actus, p. p. of agere to do, act.
1. A registar or clerk; -- used originally in courts of civil law jurisdiction, but in Europe used for a clerk or registar 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.
Expert on insurance statistics and tables of expectation of life.
Mathematician who makes statistical calculations concerning human life expectancy and other risks, on which insurance premiums are based.
The professional body in the US is the Society of Actuaries, formed 1949 by a merger of two earlier bodies.