Franglais (French: [fʁɑ̃ɡlɛ]) or Frenglish (/ˈfrɛŋɡlɪʃ/ FRENG-glish) is a French blend that referred first to the overuse of English words by French speakers and later to diglossia or the macaronic mixture of French (français) and English (anglais).

The word Franglais was first attested in French in 1959, but it was popularised by the academic, novelist, and critic René Étiemble in his denunciation of the overuse of English words in French, Parlez-vous franglais? published in 1964. Earlier than the French term was the English label Frenglish, first recorded in 1937. Other colloquial blends for French-influenced English include Franglish (recorded from 1967), Frenchlish (1974), and Fringlish (1982).

In English, Franglais means a combination of English and French. It evokes the linguistic concepts of mixed language and barbarism. Reasons for this blend could be caused by lexical gaps, native bilingualism, populations trying to imitate a language where they have no fluency (sometimes known as creoles/pidgins), or humorous intent. Franglais usually consists of either filling in gaps in one's knowledge of French with English words, using false friends, or speaking French which (although ostensibly "French") would not be understood by a French speaker who does not also have a knowledge of English (for example, by using a literal translation of English idiomatic phrases).

Some examples of Franglais are:

Geoffrey Chaucer's Prioress knew nothing of the French of France, but only that of Stratford-atte-Bow ('Cockney French'). Similar mixtures occur in the later stages of Law French, such as the famous defendant who "ject un brickbat a le dit Justice, que narrowly mist" ("threw a brickbat at the said Justice, which narrowly missed").

Another example in English literature is found in Henry V by William Shakespeare. In Act 3, Scene 4, a French princess is trying to learn English, but unfortunately, foot as pronounced by her maid sounds too much like foutre (vulgar French for 'semen', or 'to have sexual intercourse' when used as a verb) and gown like con (French for 'cunt', also used to mean 'idiot'). She decides that English is too obscene.

A literary example of the delight in mélange occurs in Robert Surtees' Jorrocks' Jaunts and Jollities:

You shall manger cinq fois every day," said she; "cinq fois," she repeated.—"Humph!" said Mr. Jorrocks to himself, "what can that mean?—cank four—four times five's twenty—eat twenty times a day—not possible!" "Oui, Monsieur, cinq fois," repeated the Countess, telling the number off on her fingers—"Café at nine of the matin, déjeuner à la fourchette at onze o'clock, dîner at cinq heure, café at six hour, and souper at neuf hour.