An Etymological Dictionary of the German Language/Tag

by Friedrich Kluge

Tag, m., ‘day, daylight,’ from the equiv. MidHG. and OHG. tac (g), m.; common to Teut. in the form dago-; comp. Goth. dags, OIc. dagr, AS. dœg, E. day (also to dawn), Du. and OSax. dag. This specifically Teut. word represents the stem, almost obsolete in Teut., of the equiv. Lat. dies, Sans. dina, OSlov. dī̆nī̆ (Goth. sin-teins, ‘daily,’ see Sündflut). To explain Teut. dago- (to which AS. dôgor, OIc. dœ́gr, from dôgoz, dôgiz, are allied), it has been connected with the Sans. root dah (for Aryan dhē̆gh, dhō̆gh?), ‘to burn’; this appears further in Lith. dègti, ‘to burn,’ dágas, dagà, ‘harvest’ (also in Sans. áhar, n., ‘day’?). Hence the base dhógho-s, common to G. Tag and Lith. dágas, means perhaps ‘the hot period of the day or year’ (comp. Ostern as a proof that names for periods of the day and year may be identical). Tag in G. denoted originally only the light period of the day; the day of twenty-four hours was called Nacht. —