1540s, one's self, "a person's self" (without distinction of gender), an emphatic form of one, with self. Hyphenated 18c.; written as one word from c. 1827, on model of himself, herself, myself, itself, etc.

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.

"unload, relieve oneself of," 1850, from off (adv.) + load (v.). Originally South African, on the model of Dutch afladen.

"one who or that which relieves," late 15c., agent noun from relieve. Baseball sense ("relief pitcher," who replaces the starting pitcher when tired or in difficulty) is attested by 1945.

"relieve or reduce pressure," by 1866, from de- + compress (v.). In early use especially "restore gradually to normal conditions  of air pressure." Figurative sense "become calm, relax" is by 1964. Related: Decompressed; decompressing.

c. 1400, exempten, "to relieve, to free or permit to be free" (from some requirement or condition, usually undesirable), from Anglo-French exempter, from exempt (adj.); see exempt (adj.). Related: Exempted; exempting.

late 13c., "help or relieve when in difficulty," from Old French succurre "to help, assist" (Modern French secourir), from Latin succurrere "to help, assist" (see succor (n.)). Related: Succored; succoring.