O.E.
frencisc "of the Franks" (see
frank). Euphemistic meaning "bad language" (
pardon my French) is from 1895. Used in many combination-words, often dealing with food or sex.
French fries is 1918 Amer.Eng., from
French fried potatoes (1894, first attested in O.Henry);
French dressing first recorded 1900;
French toast is from 1660.
French letter "condom" (c.1856),
French (v.) "perform oral sex on" (c.1917) and
French kiss (1923) all probably stem from the Anglo-Saxon equation of Gallic culture and sexual sophistication, a sense first recorded 1749 in
French novel. To take
French leave, "depart without telling the host," is 1771, from a social custom then prevalent. However, in France this is said to be called
filer à l'anglaise, lit. "to take English leave."
[french] 
), 1850–1934, U.S. novelist and short-story writer.