Source : Webster's Revised Unabridged Dictionary (1913)

Toilsome \Toil"some\ (-s[u^]m), a.
   Attended with toil, or fatigue and pain; laborious;
   wearisome; as, toilsome work.

         What can be toilsome in these pleasant walks? --Milton.
   -- {Toil"some*ly}, adv. -- {Toil"some*ness}, n.

Source : WordNet®

toilsomeness
     n : the quality of requiring extended effort [syn: {laboriousness},
          {operoseness}]