"to weary," also "to become weary," Old English teorian (Kentish tiorian) "to fail, cease; become weary; make weary, exhaust," of uncertain origin; according to Watkins possibly from Proto-Germanic *teuzon, from a suffixed form of PIE root *deu- (1) "to lack, be wanting." Related: Tired; tiring.
word-forming element meaning "lacking, cannot be, does not," from Old English -leas, from leas "free (from), devoid (of), false, feigned," from Proto-Germanic *lausaz (cognates: Dutch -loos, German -los "-less," Old Norse lauss "loose, free, vacant, dissolute," Middle Dutch los, German los "loose, free," Gothic laus "empty, vain"), from PIE root *leu- "to loosen, divide, cut apart." Related to loose and lease.
late 15c., "iron plates forming a rim of a carriage wheel," probably from tire "equipment, dress, covering" (c. 1300), a shortened form of attire (n.). The notion is of the tire as the dressing of the wheel. The original spelling was tyre, which had shifted to tire in 17c.-18c., but since early 19c. tyre has been revived in Great Britain and become standard there. Rubber ones, for bicycles (later automobiles) are from 1877. A tire-iron originally was one of the iron plates; as a device for separating a tire from a wheel, by 1909.
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Definitions of tireless
showing sustained enthusiastic action with unflagging vitality;