c.1300, "to withdraw, revoke (a decree, etc.), cancel, lift; remit," from Old French relaissier, relesser "to relinquish, quit, let go, leave behind, abandon, acquit," variant of relacher "release, relax," from Latin relaxare "loosen, stretch out" (see relax). Cf. Spanish relajar, Italian relassare.
Meaning "alleviate, ease" is mid-14c., as is sense of "free from (duty, etc.); exonerate." From late 14c. as "grant remission, forgive; set free from imprisonment, military service, etc." Also "give up, relinquish, surrender." In law, c.1400, "to grant a release of property." Of press reports, attested from 1904; of motion pictures, from 1912; of music recordings, from 1962. As a euphemism for "to dismiss, fire from a job" it is attested in American English since 1904. Related: Released; releasing.