Adaptation of Old French Louis, Looïs, Luis, from Latin Ludovīcus, from Old High German *Hlūtwīg or Frankish *Hlōdowig, from Proto-Germanic *hlūdaz (“loud, famous”) + *wīgą (“battle”). Doublet of Ludovico, Clóvis, and Aloísio.
Compare Spanish Luis, English Louis, Italian Luigi, Sicilian Luici, German Ludwig.