voluntary
vol-un-tar-y
adjective
Done or given of one's own free will, without being forced or compelled.
"She made a voluntary contribution to the local charity."
Thesaurus
Synonyms: freewill, willful, self-imposed, unpaid, wilful, willing, volunteer, unforced, uncoerced, military volunteer
Antonyms: conscript, draftee, inductee, involuntary, nonvoluntary, unvoluntary