Voluntary
/ˈvɒ.lən.tɹi/
noun
A short piece of music, often having improvisation, played on a solo instrument.
A volunteer.
A supporter of voluntarism; a voluntarist.
adjective
Done, given, or acting of one's own free will.
Done by design or intention; intentional.
“If a man accidentally kills another by lopping a tree, it is not voluntary manslaughter.”
Working or done without payment.
Synonyms: discretionary, optional, volitional, intentional, willful, honorary, pro bono, unpaid
adverb
Voluntarily.