(a.) Acting of or by one's self or by itself; -- said especially of a machine or mechanism which is made to perform of or for itself what is usually done by human agency; automatic; as, a self-acting feed apparatus; a self-acting mule; a self-acting press.

arbitrary automated automatic automatous autonomous cybernated discretional discretionary elective free free will gratuitous independent nonmandatory offered optional proffered self-active self-adjusting self-closing self-controlled self-cooking self-determined self-determining self-directed self-directing self-dumping self-governed self-governing self-lighting self-operative self-regulative self-starting self-winding self-working semiautomatic spontaneous unasked unbesought unbidden uncalled-for uncoerced uncompelled unforced uninfluenced uninvited unpressured unprompted unrequested unrequired unsolicited unsought voluntary volunteer willful