French

Etymology tree Proto-Germanic *frankô Proto-West Germanic *Frankō Proto-Indo-European *-iskos Proto-Germanic *-iskaz Proto-West Germanic *-isk Proto-West Germanic *Frankisk Old English Frencisċder. Middle English Frensch English French Inherited from Middle English Frenche, Frensch, Frensc, Frenshe, Frenk, Franche, from Old English Frenċisċ (“Frankish, French”), from Proto-West Germanic *Frankisk (“Frankish”), equivalent to Frank + -ish (compare Frankish). Cognate with Middle Low German vranksch, frenkisch, vrenkesch, vrenksch (“Frankish, French”), Middle High German vrenkisch, vrensch ("Frankish, Franconian; > German fränkisch (“Frankish, Franconian”)), Danish fransk (“French”), Swedish fransk, fransysk (“French”), Icelandic franska (“French”). Doublet of Frankish; piecewise doublet of Francis, Franz, and Francisco, which are derived from Late Latin Franciscus In reference to vulgar language, from expressions such as pardon my French in the early 19th century, originally in reference to actual (but often mildly impolite) French expressions by the upper class, subsequently adopted ironically by the lower class for English curse words under the charitable conceit that the listener would not be familiar with them. In reference to vermouth, a shortened form of French vermouth, distinguished as usually being drier than Italian vermouth.

来源：wiktionary