late 14c., from Latin voluntarius "willing, of one's free will," from voluntas "will," from the ancient accusative singular present participle of velle "to wish" (see will (v.)). Originally of feelings, later also of actions (mid-15c.). Related: Voluntarily.

mid-15c., from Late Latin involuntarius "involuntary, unwilling," from in- "not, opposite of" (see in- (1)) + Latin voluntarius "willing, voluntarily" (see voluntary). Related: Involuntarily.

1838, "theory or principal of using voluntary action rather than coercion (in politics, religion, etc.), from voluntary + -ism. (Voluntaryism in the religious sense, as opposed to establishmentarianism, is recorded from 1835.) In philosophy, "theory that the will is the basic principle," 1896, from German Voluntarismus (Tönnies, 1883).

c. 1600, "one who offers himself for military service," from French voluntaire, "one who volunteers," also as an adjective, "voluntary," from Latin voluntarius "voluntary, of one's free will," as a plural noun "volunteers" (see voluntary). Non-military sense is first recorded 1630s. As an adjective from 1640s. Tennessee has been the Volunteer State since the Mexican War, when a call for 2,800 volunteers brought out 30,000 men.

"short, quick, forward and downward motion of the head," voluntary or not, 1530s, from nod (v.).

Islamic voluntary fast on the 10th day of Muharram, Arabic Ashura', literally "tenth," from 'ashara "ten."

1640s, "the act of condescending, a voluntary inclining to equality with inferiors," from Late Latin condescensionem, noun of action from past-participle stem of condescendere "to let oneself down" (see condescend).

"not spontaneous or voluntary, strained, unnatural," 1570s, past-participle adjective from force (v.). Meaning "effected by an unusual application of force" is from 1590s. Related: Forcedly. The flier's forced landing attested by 1917.

in the philosophical sense of "voluntary agency" (embracing desire and volition), 1836, from Latin conationem (nominative conatio) "an endeavoring, effort," noun of action from past participle stem of conari "to endeavor, to try," from PIE *kona-, from root *ken- "to hasten, set oneself in motion" (see deacon).

early 15c., "voluntary," from Late Latin electivus, from elect-, past-participle stem of eligere "to pick out, choose" (see election). In U.S., in reference to school subjects studied at the student's choice, first recorded 1847. As a noun, from 1701.