odium n.

late 13c., anoien, annuien, "to harm, hurt, injure; be troublesome or vexatious to, disquiet, upset," from Anglo-French anuier, Old French enoiier "to weary, vex, anger," anuier "be troublesome or irksome to;" according to French sources these are from Late Latin inodiare "make loathsome," from Latin (esse) in odio "(it is to me) hateful," from ablative of odium "hatred," from PIE root *od- (2) "to hate" (see odium).

Also in Middle English as a noun, "feeling of irritation, displeasure, distaste" (c. 1200, still in Shakespeare), from Old French enoi, anoi "annoyance;" the same French word was borrowed into English later in a different sense as ennui. And compare Spanish enojo "offense, injury, anger;" enojar "to molest, trouble, vex." Middle English also had annoyful and annoyous (both late 14c.).

late 14c., "hateful, deserving of hatred; hated, regarded with aversion or repugnance," from Anglo-French odious, from Old French odieus (late 14c., Modern French odieux) or directly from Latin odiosus "hateful, offensive, unpleasant," from odium "hatred" (see odium). Related: Odiously; odiousness.