A long poem published in 1508 by a French choirmaster, Eloy d'Amerval, has caught the eye of historians of April Fool's Day because the text includes the phrase "poisson d'Avril," which is the French term for an "April Fool." Does this indicate that the custom of April Fool's Day was already established in France at the beginning of the 1500s?
Probably not. Or, at least, we can't conclude that from d'Amerval's poem, because the manner in which he used the phrase "poisson d'Avril" doesn't indicate that he associated the term with folly or April 1. Instead, for him it seemed to be a slang term for a pimp or matchmaker. Etymologists suggest that this was, in fact, the original meaning of the term, and that it only evolved to mean an "April Fool" in the 17th century.