An Etymological Dictionary of the German Language/Annotated/müssen

by Friedrich Kluge

müssen, anom. verb, ‘to be obliged; must,’ from Middle High German müeȥen, Old High German muoȥan, preterite present, ‘to like, be able; be allowed, be obliged’ (see Muße); compare Old Saxon motân, Dutch moeten, ‘to be obliged; ought,’ Anglo-Saxon *motan, ‘to be allowed, be able, like, be obliged,’ in English only the preterite must (Anglo-Saxon môste, ‘was obliged’) has been preserved with the meaning of the present; Gothic gamôtan, ‘to take place, have room.’ The origin of these cognates is doubtful; they can scarcely be connected with messen.