Source : Webster's Revised Unabridged Dictionary (1913)

Slothful \Sloth"ful\, a.
   Addicted to sloth; inactive; sluggish; lazy; indolent; idle.

         He also that is slothful in his work is brother to him
         that is a great waster.                  --Prov. xviii.
                                                  9.
   -- {Sloth"ful*ly}, adv. -- {Sloth"ful*ness}, n.

Source : WordNet®

slothfulness
     n : a disinclination to work or exert yourself [syn: {sloth}]