An Etymological Dictionary of the German Language/irre

by Friedrich Kluge

irre, adj., ‘in error, astray, insane, confused,’ from the equiv. MidHG. irre, OHG. irri, adj. (OHG. also ‘provoked’); corresponding to AS. yrre, ‘provoked, angry.’ Allied to Goth. airzeis, ‘astray, misled’ (HG. rr equal to Goth. rz). Anger was regarded as an aberration of mind (comp. also Lat. delirare, allied to lira, ‘furrow,’ prop. ‘rut’). The root ers appears also in Lat. errare, ‘to go astray’ (for *ersare), error, ‘mistake’ (for *ersor); allied also to Sans. irasy, ‘to behave violently, be angry’?. —