An Etymological Dictionary of the German Language/erst
erst, adj., ‘first,’ from MidHG. êrst, OHG. êrist, ‘the first’; corresponding to OSax. êrist, AS. œ̂rest, ‘the first’; superlat. of the compar. form cited under eher. Goth. airis, adv., formerly,’ airiza, ‘predecessor, ancestor,’ OHG. êriro (êrro), ‘predecessor’; the positive is preserved in Goth. air. adv., ‘early,’ AS. œ̂r, adj. adv., ‘early,’ OIc. ár, adv., ‘early’ (OHG. êr-acchar, ‘‘awake early’). Probably the stem air-, on which the word was based, was used orig. like früh, only of the hours of the day. It is connected most probably with Gr. ἦρς, ‘early in the morning.’