early 15c., "mitigation, relief," from Medieval Latin alleviationem (nominative alleviatio), noun of action from past-participle stem of alleviare "lift up, raise," figuratively "to lighten (a burden), comfort, console," from assimilated form of Latin ad "to" (see ad-) + levis "light" in weight (from PIE root *legwh- "not heavy, having little weight").
late 14c., "a rising, height of something, height to which something is elevated," from Old French elevation and directly from Latin elevationem (nominative elevatio) "a lifting up," noun of action from past-participle stem of elevare "lift up, raise," figuratively, "to lighten, alleviate," from ex "out" (see ex-) + levare "to lighten; to raise," from levis "light" in weight (from PIE root *legwh- "not heavy, having little weight"). Meaning "act of elevating" is from 1520s.
early 15c., "conjuring tricks, sleight of hand," from Old French léger de main "quick of hand," literally "light of hand." Léger "light" in weight (Old French legier, 12c.) is from Latin levis "light" (from PIE root *legwh- "not heavy, having little weight"). It is cognate with Spanish ligero, Italian leggiero "light, nimble" (hence also leger line or ledger line in music). Main "hand" is from Latin manus (from PIE root *man- (2) "hand").
late 14c., oblivioun, "state or fact of forgetting, forgetfulness, loss of memory," from Old French oblivion (13c.) and directly from Latin oblivionem (nominative oblivio) "forgetfulness; a being forgotten," from oblivisci (past participle oblitus) "forget," which is of uncertain origin.
Perhaps originally "even out, smooth over, efface," from ob "over" (see ob-) + root of lēvis "smooth," but de Vaan and others find that "a semantic shift from 'to be smooth' to 'to forget' is not very convincing." However no better explanation has emerged. Latin lēvis also meant "rubbed smooth, ground down," from PIE *lehiu-, from root *(s)lei- "slime, slimy, sticky" (see slime (n.)); for sense evolution, compare obliterate.
Meaning "state or condition of being forgotten or lost to memory" is from early 15c. In English history, the Acts of Oblivion use the word in the sense of "intentional overlooking" (1610s), especially of political offenses. Related: Obliviously; obliviousness.
Oblivion is the state into which a thing passes when it is thoroughly and finally forgotten. ... Forgetfulness is a quality of a person: as a man remarkable for his forgetfulness. ... Obliviousness stands for a sort of negative act, a complete failure to remember: as a person's obliviousness of the proprieties of an occasion. [Century Dictionary]
late 14c., releven, "alleviate (pain, etc.) wholly or partly, mitigate; afford comfort; allow respite; diminish the pressure of," also "give alms to, provide for;" also figuratively, "take heart, cheer up;" from Old French relever "to raise, relieve" (11c.) and directly from Latin relevare "to raise, alleviate, lift up, free from a burden," from re-, here perhaps an intensive prefix (see re-), + levare "to lift up, lighten," from levis "not heavy" (from PIE root *legwh- "not heavy, having little weight").
The notion is "to raise (someone) out of trouble." From c. 1400 as "advance to the rescue in battle, bring help to a besieged place;" also "return from battle; recall (troops)." Meaning "release from duty" is from early 15c. Related: relieved; relieving.