Synonyms and related words :
arbitrary, autonomous, discretional, discretionary, elective, free, free will, gratuitous, independent, nonmandatory, offered, optional, proffered, self-acting, self-active, self-determined, self-determining, spontaneous, unacceptable, unagreeable, unasked, unasked-for, unbesought, unbidden, uncalled-for, uncoerced, uncompelled, undesirable, undesired, unforced, uninfluenced, unpressured, unprompted, unrequested, unrequired, unsolicited, unsought, unwanted, unwelcome, unwished, voluntary, volunteer, willful