An Etymological Dictionary of the German Language/Annotated/früh
früh, adjective, adverb, ‘early, premature(ly),’ from Middle High German vrüeje, adjective, ‘early,’ vruo, adverb, ‘early’ (hence sometimes the Modern High German fruh unmodified); Old High German fruoji, adjective fruo, adverb, ‘early’; compare Dutch vroeg, adjective and adverb, ‘early.’ Gothic *frô (or rather *frauô for *frôô?), adverb, is wanting. Pre-Teutonic prô- appears also in Greek πρωΐ, ‘early, early in the morning,’ πρωΐα, feminine, ‘morning,’ πρώϊος, ‘early’; akin to Sanscrit prâtar, adverb, ‘early in the morning.’ Allied more remotely to vor, Fürst, vordere, &c. (also frisch?). It is curious that the Old Aryan adverb, in the sense of ‘early in the morning,’ is restricted to German. In Scandinavian, English, and Gothic it is wanting; the words used being Gothic air, Old Icelandic ár, Anglo-Saxon œ̂r, ‘early in the morning’ (see ehe). Moreover, its special meaning was universally diffused at an early period. See Frühling.