a. [ L. indefatigabilis: cf. OF. indefatigable. See In- not, and Defatigable, and cf. Infatigable. ] Incapable of being fatigued; not readily exhausted; unremitting in labor or effort; untiring; unwearying; not yielding to fatigue;
Upborne with indefatigable wings. Milton.
n. Indefatigable quality; unweariedness; persistency. Parnell. [ 1913 Webster ]