err (v.) Look up err at Dictionary.com
c.1300, from Old French errer "go astray, lose one's way; make a mistake; transgress," from Latin errare "wander, go astray, be in error," from PIE root *ers- (1) "be in motion, wander around" (cognates: Sanskrit arsati "flows;" Old English ierre "angry, straying;" Old Frisian ire "angry;" Old High German irri "angry," irron "astray;" Gothic airziþa "error, deception;" the Germanic words reflecting the notion of anger as a "straying" from normal composure). Related: Erred; erring.