An Etymological Dictionary of the German Language/als

by Friedrich Kluge

als, conj., ‘as,’ from MidHG. als, álse, álsô, ‘likewise, thus, as, as if, because,’ hence prop. identical with also; OHG. alsô, ‘likewise, like,’ is a compound of al, ‘entirely,’ and sô, ‘thus,’ like the exactly corresponding AS. ealswâ, whence E. as, from eal, ‘entirely,’ and swâ, ‘so.’