From Middle English dere, from Old English dæru, daru (“injury, hurt, harm, damage, calamity; loss, deprivation”), from Proto-Germanic *darō (“damage, injury”), from Proto-Indo-European *dʰō(w)- (“to sharpen”). Cognate with Middle Dutch dare, dere, Middle Low German dere, Old High German tara (“damage, injury”).
(third-person singular simple present deres, present participle dering, simple past and past participle dered)
From Middle English deren, derien, from Old English derian (“to damage, injure, hurt, harm”), from Proto-Germanic *darjaną (“to injure, harm”), from Proto-Indo-European *dʰō(w)- (“to sharpen”). Cognate with Scots dere, deir (“to harm, hurt, injure”), Saterland Frisian dera (“to injure, damage”), West Frisian deare, derre (“to harm, injure”), Dutch deren (“to injure, damage, scathe”), Middle High German tern (“to injure”). Related to dart.