"North African, Berber, one of the race dwelling in Barbary," late 14c., from Old French More, from Medieval Latin Morus, from Latin Maurus "inhabitant of Mauretania" (Roman northwest Africa, a region now corresponding to northern Algeria and Morocco), from Greek Mauros, perhaps a native name, or else cognate with mauros "black" (but this adjective only appears in late Greek and may as well be from the people's name as the reverse).
Also applied to the Arabic conquerors of Spain. Being a dark people in relation to Europeans, their name in the Middle Ages was a synonym for "Negro;" later (16c.-17c.); being the nearest Muslims to Western Europe, it was used indiscriminately of Muslims (Persians, Arabs, etc.) but especially those in India. Cognate with Dutch Moor, German Mohr, Danish Maurer, Spanish Moro, Italian Moro. Related: Mooress.
The origin of the ethnic name is uncertain; it traditionally is said to be from the old Germanic word *frankon "javelin, lance" (compare Old English franca "lance, javelin"), their preferred weapon, but the reverse may be the case. Compare also Saxon, traditionally from root of Old English seax "knife." The adjectival sense of "free, at liberty" (see frank (adj.)) probably developed from the tribal name, not the other way round. It was noted by 1680s that, in the Levant, this was the name given to anyone of Western nationality (compare Feringhee and lingua franca).