Proli- comes from the Latin proles meaning offspring and –fic derives from facere, to make. Hence prolific = offspring-making.
(Proles is also part of the word proletarian, which literally means “concerning offspring.” The citizens of the lowest class in ancient Rome were propertyless people, exempted from taxes and military service, who served the state only by having children.)
As to the use of “prolific”:
- Common use: Dickens was a prolific writer, etc.
- Uncommon use: The Life and Times of Albert Pierrepoint, Britain’s most prolific hangman.
Considering Pierrepoint’s unusually abundant works, the use of the word in this case is entirely proper. It is believed that Pierrepoint executed at least 433 men and 17 women, including “Lord Haw Haw” and some 200 Nazi war criminals. A figure of 608 people was given in the credits at the end of the film Pierrepoint: The Last Hangman, although no source for this information was indicated.
The appropriateness of the word “prolific” is not reduced in any way by a significant observation in his autobiography, Executioner: Pierrepoint, published in 1974: “I have come to the conclusion that executions solve nothing, and are only an antiquated relic of a primitive desire for revenge, which takes the easy way and hands over the responsibility for revenge to other people.”