An Etymological Dictionary of the German Language/neigen
neigen, vb., ‘to tilt, bend, incline,’ from MidHG. nîgen, str. vb., ‘to bow,’ and neigen, wk. vb., ‘to cause to bow, humiliate, lower’; OHG. nîgan, from hnîgan, str. vb., ‘to bow,’ and neigen, wk. vb., ‘to incline, bend.’ It corresponds to OSax. hnîgan, hnêgian, AS. hnîgan, hnœ̂gan, Goth. hneiwan, vb., ‘to bow, sink,’ hnaiwjan, vb., ‘to humiliate, bend’ (for *hneigwan, *hnaigwjan); the wk. vb. is the causative of the str. vb. The Teut. root hnîgw, from pre-Teut. knī̆gh (or rather knī̆q?), is uncertain in the other Aryan languages. Perhaps Lat. co-nîveo, nîco, nicto, ‘to wink, nod,’ are connected with the Teut. cognates.