Source : Webster's Revised Unabridged Dictionary (1913)

Tiredness \Tired"ness\, n.
   The state of being tired, or weary.

Source : WordNet®

tiredness
     n : temporary loss of strength and energy resulting from hard
         physical or mental work; "he was hospitalized for extreme
         fatigue"; "growing fatigue was apparent from the decline
         in the execution of their athletic skills"; "weariness
         overcame her after twelve hours and she fell asleep"
         [syn: {fatigue}, {weariness}]