early 15c., pulsacioun, "pulsing of the blood, throbbing," from Latin pulsationem (nominative pulsatio) "a beating or striking," noun of action from past-participle stem of pulsare "to beat, strike, push against' hammer, keep hitting," figuratively "drive forth, disturb, disquiet," frequentative of pellere (past participle pulsus) "to beat, strike" (from PIE root *pel- (5) "to thrust, strike, drive").
mid-14c., "condition of being in active operation; practice for the sake of training," from Old French exercice (13c.) "exercise, execution of power; physical or spiritual exercise," from Latin exercitium "training, physical exercise" (of soldiers, horsemen, etc.); "play;" in Medieval Latin also of arts, from exercitare, frequentative of exercere "keep busy, keep at work, oversee, engage busily; train, exercise; practice, follow; carry into effect; disturb, disquiet," from ex "off" (see ex-) + arcere "keep away, prevent; contain, enclose," from PIE *ark- "to hold, contain, guard" (see arcane).
The original notion in the Latin verb is obscure. Meaning "physical activity for fitness, etc." first recorded in English late 14c. Also from late 14c. as "a carrying out of an action; a doing or practicing; a disciplinary task." In reference to written schoolwork from early 17c. The ending was abstracted for formations such as dancercise (1967); jazzercise (1977); and boxercise (1985).
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.).