Synonyms of voluntary in English:

voluntary


See definition of voluntary

adjective

1‘attendance at lectures is voluntary’

SYNONYMS
optional, discretionary, at one's discretion, elective, non-compulsory, non-mandatory, not required, open, open to choice, volitional, up to the individual
permissive
rare discretional
ANTONYMS

compulsory, obligatory

2‘she spent some time doing voluntary work’

SYNONYMS
unpaid, unsalaried, without pay, without payment, free of charge, without charge, for nothing, for free
honorary, volunteer, unrewarded
pro bono, pro bono publico
ANTONYMS

paid