Q From B J Wise: I’ve just read a suspicious description of the origin of the word fornication. Supposedly, it comes from fornacis, the Latin for furnace, which has to do with prostitutes operating out of bakeries and advertising with bread baked in the shape of penises. They would wait for the oven to cool, and crawl inside to “heat the ovens back up again”. Is there any merit to this?
A That’s an utterly unfounded but delightful story. The writer has vaguely recalled the real origin and has built a shaky tower of invention on no foundation whatsoever except a misunderstanding of Latin vocabulary.
For the Romans a furnace was a fornax (fornacis is actually the genitive form, “of a furnace”, best known among astronomers in the formal names of stars in the constellation Fornax, such as Beta Fornacis). The word the teller of your tale was searching for is fornix, an arch or vaulted chamber. It’s true that furnaces and bread ovens were often built in an arched shape, and some writers have consequently sought to derive fornix from fornax, but the two words had distinct senses in classical Latin.
A fornix might be a triumphal arch marking a successful battle or a mundane one supporting the upper floor of a Roman building. Arched passages in public buildings such as the Stadium and Colosseum in Rome were popular with prostitutes seeking trade. Brothels of the poorer sort were often established in vaulted cellars. So fornix became a slang term for a house of ill repute.
The late Latin verb fornicari and the noun fornicationem came from fornix. English took over the noun from French around 1300 but the verb only appeared 250 years later.
It’s curious that the noun was recorded a century ago in the English Dialect Dictionary as in use in several English dialects for telling lies. A fornicator was a liar and a fornicating person was deceitful or treacherous. We may guess this evolved because a person who was suspected of sex outside marriage was strongly tempted to tell lies about it.