Source : Webster's Revised Unabridged Dictionary (1913)

Tire \Tire\, v. i. [imp. & p. p. {Tired}; p. pr. & vb. n.
   {Tiring}.] [OE. teorien to become weary, to fail, AS. teorian
   to be tired, be weary, to tire, exhaust; perhaps akin to E.
   tear to rend, the intermediate sense being, perhaps, to wear
   out; or cf. E. tarry.]
   To become weary; to be fatigued; to have the strength fail;
   to have the patience exhausted; as, a feeble person soon
   tires.

Source : WordNet®

tiring
     adj : producing exhaustion; "an exhausting march"; "the visit was
           especially wearing" [syn: {exhausting}, {wearing}, {wearying}]