compulsory Antonyms

optional unimportant willful willing willed volunteer voluntary volitional unessential unconsequential self-imposed selective purposeless irrelevant unnecessary willing and able unstipulated unrestrictive unrequested uncompensated unneeded elidable unforced nonobligatory nonmandatory incidental uncoerced highly controversial prudential omissible free elective dispensable discretionary discretional deliberate auxiliary armless arbitral ancillary accountable freewill frivolous immaterial nonessential negligible needless minor liberalized insubstantial