1590s, "one who performs mechanical or surgical operations," agent noun from operate (v.) or from Late Latin operator "a worker." Meaning "one who carries on business shrewdly" is from 1828. Specific sense of "one who works a telephone switchboard" (1884) grew out of earlier meaning "one who works a telegraph" (1847).
1809, "worker, operator, artisan," from operative (adj.); sense of "secret agent, spy" is attested from 1930, probably from its use by the Pinkerton Detective Agency as a title for their private detectives (1905) to avoid the term detective.
The operator first muttered over the crystal (a beryl was preferred) certain formulas of prayer, and then gave it into the hands of a young man or a virgin, who thereupon, by oral communication from spirits in the crystal, or by written characters seen in it, was supposed to receive the information desired. [Century Dictionary]
mid-14c., multiplicacioun, "any increase in size, number, or amount; act or process of increasing in number," from Old French multiplicacion (12c.) "multiplication, duplication; multiplicity, diversity," from Latin multiplicationem (nominative multiplicatio), noun of action from past-participle stem of multiplicare "to multiply, increase" (see multiply). The arithmetical sense of "process in which one number is considered as an operator on another" is attested from late 14c.
1896, "a motorist," from French chauffeur, literally "stoker," operator of a steam engine, French nickname for early motorists, from chauffer "to heat," from Old French chaufer "to heat, warm up; to become hot" (see chafe). The first motor-cars were steam-driven. Sense of "professional or paid driver of a private motor car" is from 1902.
The '95 Duryea wagon, which won the Chicago contest last Fall, was exhibited at the Detroit Horse Show last week. Charles B. King, treasurer of the American Motor League, acted as "chauffeur," as the French say. [The Horseless Age, April 1896]