The only free and comprehensive online etymological dictionary of the Spanish language
mujer f. (Noun) "woman"
11th cent. Old Spanish muller. 12th cent. Old Spanish mugier, muger. From Latin mulier 'id.' Possibly a comparative of mollis "soft," "weak" but see de Vaan (2014) for a discussion of this argument's serious problems. If not connected to mollis, then of unknown origin. For a continued etymology of mollis, see muelle.
Asturian muyer, Portuguese mulher, Galician muller, Catalan muller, Italian moglie, Aromanian muljari, Romanian muiere, Sardinian mugere