The story
The first known occurrence of the term in its Latin form (Respublica literaria) is in a letter by Francesco Barbaro to Poggio Bracciolini dated July 6, 1417.
Etymology from Wiktionary, CC BY-SA 4.0.
Republic of Letters
Today it means: The intellectual community in the late 17th and 18th centuries in Europe and the Americas, exchanging ideas by circulating handwritten letters. Full definition →