Source : Webster's Revised Unabridged Dictionary (1913)

Aimless \Aim"less\, a.
   Without aim or purpose; as, an aimless life. --
   {Aim"less*ly}, adv. -- {Aim"less*ness}, n.

Source : WordNet®

aimlessness
     n : the quality of lacking any definite purpose [syn: {purposelessness}]
         [ant: {purposefulness}]