The Collaborative International Dictionary of English v.0.48:

Painful \Pain"ful\, a.
   1. Full of pain; causing uneasiness or distress, either
      physical or mental; afflictive; disquieting; distressing.
      --Addison.
      [1913 Webster]

   2. Requiring labor or toil; difficult; executed with
      laborious effort; as a painful service; a painful march.
      [1913 Webster]

   3. Painstaking; careful; industrious. [Obs.] --Fuller.
      [1913 Webster]

            A very painful person, and a great clerk. --Jer.
                                                  Taylor.
      [1913 Webster]

            Nor must the painful husbandman be tired. --Dryden.
      [1913 Webster]

   Syn: Disquieting; troublesome; afflictive; distressing;
        grievous; laborious; toilsome; difficult; arduous.
        [1913 Webster] -- Pain"ful*ly, adv. --
        Pain"ful*ness, n.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

painfulness \pain"ful*ness\ n.
   Emotional distress; a fundamental feeling that people try to
   avoid.

   Syn: pain.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

painfulness
    n 1: emotional distress; a fundamental feeling that people try
         to avoid; "the pain of loneliness" [syn: pain,
         painfulness] [ant: pleasance, pleasure]
    2: the quality of being painful; "she feared the painfulness of
       childbirth" [syn: painfulness, distressingness]