discharge (n.)

late 14c., "relief from misfortune," see discharge (v.). Meaning "release from work or duty" is from early 15c.

discharge (v.)

early 14c., "to exempt, exonerate, release," from Old French deschargier (12c., Modern French décharger) "to unload, discharge," from Late Latin discarricare, from dis- "do the opposite of" (see dis-) + carricare "to load a wagon or cart," from Latin carrus "two-wheeled wagon" (see car).

Meaning "to unload, to free from" is late 14c. Of weapons, from 1550s. The electrical sense is first attested 1748. Meaning "to fulfill, to perform one's duties" is from c. 1400. Related: Discharged; discharging.