Voluntary
vol·un·tar·y
/ˈvälənˌterē/
adjective
1. 1.
done, given, or acting of one's own free will."we are funded by voluntary contributions"
2. Synonyms
optional, discretionary, at one's discretion, elective, noncompulsory, nonmandatory, not required, open, open to choice, volitional, up to the individual; permissive; rarediscretional
"attendance at lectures is voluntary
Information from: google
