the medieval Norman and English dialect of Old French
See also Anglo-French (sense 3)
Norman French in American English
1.
the French of the Normans or Normandy, as spoken in England by the Norman conquerors; Anglo-French: it was not imposed on the English as an official language at the Conquest, but gained legal and administrative currency after the accession of Eleanor of Aquitaine as queen (1154)
2.
the form of this language used as the legal jargon of England until the late 17th cent.