WordNet sense 1 (a substance that is emitted or released):

emission

WordNet sense 2 (any of several bodily processes by which substances go out of the body):

expelling

WordNet sense 3 (electrical conduction through a gas in an applied electric field):

arc, spark, electric discharge, electric arc

WordNet sense 4 (the pouring forth of a fluid):

outpouring, run

WordNet sense 5 (complete or carry out):

complete, dispatch

WordNet sense 6 (free from obligations or duties):

free

WordNet sense 7 (leave or unload, especially of passengers or cargo):

drop, unload, drop off, set down, put down

WordNet sense 8 (the act of venting):

venting

WordNet sense 9 (go off or discharge):

fire, go off

WordNet sense 10 (release from military service):

muster out

WordNet sense 11 (pronounce not guilty of criminal charges):

acquit, clear, exculpate, exonerate, assoil

WordNet sense 12 (become empty or void of its content):

empty

WordNet sense 13 (the termination of someone's employment (leaving them free to depart)):

dismissal, liberation, release, sack, sacking, firing, dismission, release

WordNet sense 14 (a formal written statement of relinquishment):

waiver

WordNet sense 15 (the act of discharging a gun):

firing off

WordNet sense 16 (eliminate (substances) from the body):

eject, expel