The Collaborative International Dictionary of English v.0.48:

Slothful \Sloth"ful\, a.
   Addicted to sloth; inactive; sluggish; lazy; indolent; idle.
   [1913 Webster]

         He also that is slothful in his work is brother to him
         that is a great waster.                  --Prov. xviii.
                                                  9.
   [1913 Webster] -- Sloth"ful*ly, adv. -- Sloth"ful*ness,
   n.
   [1913 Webster]