Definition of: voluntary

(vol′ən·ter′ē) adjective
1. Proceeding from the will or from one's own free choice: voluntary murder; specifically, unconstrained; intentional; volitional.
2. Endowed with, possessing, or exercising will or free choice: a voluntary donor.
3. Effected by choice or volition; acting without constraint.
4. Subject to or directed by the will, as a muscle or movement.
5. Of or relating to voluntaryism.
6. Law Unconstrained of will; done without compulsion; performed without legal obligation; also, done without valuable consideration; gratuitous. See synonyms under SPONTANEOUS.
—noun plural ·tar·ies
1. Any work or performance not compelled or imposed by another.
2. Music a An organ solo, often improvised, played before, during, or after a service. b Rare A piece of music, usually spontaneous, played or sung as a prelude.
3. Obs. A volunteer. [<OF voluntaire <L voluntarius <voluntas will]
—vol′un·tar′i·ly adverb
—vol′un·tar′i·ness noun