That operates to produce an effect.
Any of a class of behaviors that produce consequences by operating (i.e., acting) upon the environment.
An operative person or thing.
Done by design or intention; intentional.
Done, given, or acting of one's own free will.
Of or relating to voluntarism.
Endowed with the power of willing.
Working or done without payment.
A supporter of voluntarism; a voluntarist.
A short piece of music, often having improvisation, played on a solo instrument.
A volunteer.