c. 1200, transitive, "to make worried or depressed; to make angry, enrage;" also "to be physically painful, cause discomfort;" c. 1300 as "cause grief to, disappoint, be a cause of sorrow;" also "injure, harass, oppress," from tonic stem of Old French grever "afflict, burden, oppress," from Latin gravare "make heavy; cause grief," from gravis "weighty" (from PIE root *gwere- (1) "heavy"). Intransitive sense of "be sorry, lament" is from c. 1400. Related: Grieved; grieving.
It forms all or part of: aggravate; aggravation; aggrieve; bar (n.4) "unit of pressure;" bariatric; baritone; barium; barometer; blitzkrieg; brig; brigade; brigand; brigantine; brio; brut; brute; charivari; gravamen; grave (adj.); gravid; gravimeter; gravitate; gravity; grief; grieve; kriegspiel; guru; hyperbaric; isobar; quern; sitzkrieg.
It is the hypothetical source of/evidence for its existence is provided by: Sanskrit guruh "heavy, weighty, venerable;" Greek baros "weight," barys "heavy in weight," often with the notion of "strength, force;" Latin gravis, "heavy, ponderous, burdensome, loaded; pregnant;" Old English cweorn "quern;" Gothic kaurus "heavy;" Lettish gruts "heavy."
1580s, "to sorrow or grieve over with another," from Late Latin condolere "to suffer with another," from assimilated form of com "with, together" (see con-) + dolere "to grieve" (see doleful). Meaning "express condolences, speak sympathetically to one in pain, grief, or misfortune" is recorded from 1650s. Related: Condoled; condoling.
late 14c., regreten, "to look back with distress or sorrowful longing; to grieve for on remembering," from Old French regreter "long after, bewail, lament someone's death; ask the help of" (Modern French regretter), from re-, intensive prefix (see re-), + -greter, which is possibly from Frankish or some other Germanic source (compare Old English grætan "to weep;" Old Norse grata "to weep, groan"), from Proto-Germanic *gretan "weep." "Not found in other Romance languages, and variously explained" [Century Dictionary].
From 1550s as "to grieve at (an event, action, revelation of facts, etc.)." Related: Regretted; regretting. Replaced Old English ofþyncan, from of- "off, away," here denoting opposition, + þyncan "seem, seem fit" (as in methinks).
mid-13c., monen, "mourn (someone); regret, bewail;" c. 1300, "to lament inarticulately, grieve; utter mournfully;" probably from Old English *mānan, a variant of mænan "to lament" (see moan (n.)). From late 14c. as "complain, tell one's troubles." From 1724 as "to make a low sound expressive of physical or mental suffering." Related: Moaned; moaning.