The term franklin denotes a member of a social class or rank in England in the 12th to 15th centuries. In the period when Middle English was in use, a franklin was simply a freeman; that is, a man who was not a serf, in the feudal system under which people were tied to land which they did not own, in bondage to a member of the nobility who owned that land. The surname "Fry", derived from the Old English "frig" ("free born"), indicates a similar social origin.
The meaning of the word "franklin" evolved to mean a freeholder; that is, one who holds title to real property in fee simple. In the 14th and 15th centuries, franklin was "the designation of a class of landowners ranking next below the landed gentry".
With the definite end of Feudalism, this social class disappeared as a distinct entity, the legal provisions for "a free man" being applied to the general population. The memory of that class was preserved in the use of "Franklin" as a family name, the most well-known being US founding father Benjamin Franklin.
According to the OED, the term "franklin" is derived from Middle English franklen, frankeleyn, francoleyn, from Anglo-Latin francalanus a person owning francalia, "territory held without dues". Collins mentions the Anglo-French fraunclein, "a landowner of free, but not noble birth", from Old French franc free + -lein, "-ling", formed on the model of "chamberlain"; all these go back to Late Latin francus "free" or "a free man", from Frankish *Frank, "a freeman", literally, "a Frank"; cognate with Old High German Franko, which meant a German from a confederation in Franconia of which a branch conquered Gaul, from which event is also explained the name of the country France.