An Etymological Dictionary of the German Language/Annotated/laut
laut, adjective, ‘loud,’ from the equivalent Middle High German and Old High German lût (for an earlier hlût, Gothic *hlûda-); a common Teutonic adjective (compare Dutch luid, Anglo-Saxon hlûd, English loud), which, like falt, alt, tot, gewiß, traut, zart, -haft, kund, satt, wund, was originally an old participle in to (Latin tus, Greek τος, Indian tas). The meaning of *klû-dâ-s, pre-Teutonic klû-tó-s, from the root klū̆, ‘to hear,’ is literally ‘audible, heard.’ Another shade of meaning was assumed by the Aryan participle in the cognate languages — Sanscrit çrutás, Greek κλυτός, Latin inclŭtus, ‘famous.’ In Teutonic also there are traces of the short vowel (hlŭda-), especially in proper names, Ludwig, Lothar, Ludolf, Chlothilde, &c. Moreover, the root klū̆ (Greek κλύω, ‘I hear,’ κλέος, ‘fame’; Indian çrávas, ‘fame’; Old Slovenian sluti, ‘to be called,’ slovo for *slevo, ‘word’; Latin cluo, clueo, ‘to hear oneself called’) is also widely diffused in Old Teutonic; Gothic hliuma, ‘hearing, ear,’ Old Icelandic hljómr, Anglo-Saxon hleóþor, ‘tone, voice, melody. Compare lauschen and Leumund.