1610s, "to lay waste, devastate" (obsolete); 1620s, "to vex by repeated attacks," from French harasser "tire out, vex" (16c.), which is of uncertain origin; possibly from Old French harer "stir up, provoke; set a dog on" (according to Watkins, from Frankish *hara "over here, hither," from Proto-Germanic *hi‑, from PIE *ki-, variant form of root *ko-, the stem of demonstrative pronoun meaning "this"), and perhaps blended with Old French harier "to harry, draw, drag" [Barnhart]. Related: Harassed; harassing.
Harass, as applied to mind or body, suggests the infliction of the weariness that comes from the continuance or repetition of trying experiences, so that there is not time for rest. Torment implies the infliction of acute pain, physical or mental, and is frequently used in the sense of harassing by frequent return. [Century Dictionary, 1897]
"to torture, torment, inflict very severe pain on," as if by crucifying, 1560s, from Latin excruciatus, past participle of excruciare "to torture, torment, rack, plague;" figuratively "to afflict, harass, vex, torment," from ex "out, out from; thoroughly" (see ex-) + cruciare "cause pain or anguish to," literally "crucify," from crux (genitive crucis) "a cross" (see crux).
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 both 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.).
In Middle English, also of physical pain. Meaning "excite to wrath, make angry" is from late 14c. Related: Angered; angering.
Old English fretan "devour, feed upon, consume," from Proto-Germanic compound *fra-etan "to eat up," from *fra- "completely" (from PIE root *per- (1) "forward," hence "through") + *etan "to eat" (from PIE root *ed- "to eat"). Cognates include Dutch vreten, Old High German frezzan, German fressen, Gothic fraitan.
Used of monsters and Vikings; in Middle English used of animals' eating. Notion of "wear away by rubbing or scraping" (c. 1200) might have come to this word by sound-association with Anglo-French forms of Old French froter "to rub, wipe; beat, thrash," which is from Latin fricare "to rub" (see friction). Figurative use is from c. 1200, of emotions, sins, vices, etc., "to worry, consume, vex" someone or someone's heart or mind, from either the "eating" or the "rubbing" sense. Intransitive sense "be worried, vex oneself" is by 1550s. Modern German still distinguishes essen for humans and fressen for animals. Related: Fretted; fretting. As a noun, early 15c., "a gnawing," also "the wearing effect" of awareness of wrongdoing, fear, etc.