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]WordNet (r) 3.0 (2006):
slothfulness n 1: a disinclination to work or exert yourself [syn: sloth, slothfulness]