Source : Webster's Revised Unabridged Dictionary (1913)

Tiresome \Tire"some\, a.
   Fitted or tending to tire; exhausted; wearisome; fatiguing;
   tedious; as, a tiresome journey; a tiresome discourse. --
   {Tire"some*ly}, adv. -- {Tire"some*ness}, n.

Source : WordNet®

tiresomeness
     n : dullness owing to length or slowness [syn: {tediousness}, {tedium}]