Barr- is a pre-Indo-European linguistic root meaning 'wooded hill', 'natural barrier'.Éric Vial, Les noms de villes et de village, Belin, 1983,
In addition to the common noun bar, it explains many place names as:
Barr, commune of Alsace, France Bar, commune of Corrèze, Limousin France Bar-sur-Aube and Bar-sur-Seine, communes of Aube, Champagne, France Bar-le-Duc, commune of Lorraine, France
but not Le Bar-sur-Loup, a former Albarn > Aubarn.
In the Alps, the word applies to rocky escarpments: la Barre des Écrins is a mountain in the French Alps.
This root should not be mistaken for the Basque root Bar- / ibar 'valley'.
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