relieveyoudaoicibaDictYouDict[relieve 词源字典]
relieve: [14] Relieve goes back via Old French relever to Latin relevāre ‘raise again’, a compound verb formed from the prefix re- ‘again’ and levāre ‘raise’ (source of English elevate, levy, etc). Its metaphorical extension to ‘lighten, alleviate’ began in Latin. The derived noun relief reached English in two phases. First, in the standard sense ‘easing, alleviation’, via Anglo-Norman relef in the 14th century; and then, in the 17th century, via French from Italian relievo in the sense ‘raised area in a design’ – a return to the etymological meaning ‘raise’.
=> elevate, levy, relevant[relieve etymology, relieve origin, 英语词源]
relieve (v.)youdaoicibaDictYouDict
late 14c., "alleviate (pain, etc.), 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-, intensive prefix (see re-), + levare "to lift up, lighten," from levis "not heavy" (see lever).

The notion is "to raise (someone) out of trouble." From c. 1400 as "advance to the rescue in battle;" also "return from battle; recall (troops)." Meaning "release from duty" is from early 15c. Related: relieved; relieving.