An Etymological Dictionary of the German Language/zag
zag, adj. ‘faint-hearted, shy, irresolute,’ from MidHG. zage, OHG. zago, zag, adj., ‘faint-hearted, cowardly.’ A derivative of ModHG. zagen, ‘to lack courage, hesitate’ (comp. wach and wachen), MidHG. zagen, OHG. zagên. It is not probable that the word was borrowed, in spite of the few cognates of the Teut. stem tag. This is probably derived from a Goth. *at-agan (1st sing. *ataga, equiv. to Ir. ad-agur, ‘to be afraid’) by apocope of the initial vowel; at is probably a pref. Goth. agan, ‘I am afraid,’ is based on the widely diffused OTeut. root ag (Aryan agh), ‘to be afraid,’ with which Gr. ἄχος, ‘pain, distress,’ is also connected.