The Collaborative International Dictionary of English v.0.48:

Uncomfortable \Un*com"fort*a*ble\, a.
   1. Feeling discomfort; uneasy; as, to be uncomfortable on
      account of one's position.
      [1913 Webster]

   2. Causing discomfort; disagreeable; unpleasant; as, an
      uncomfortable seat or situation.
      [1913 Webster]

            The most dead, uncomfortable time of the year.
                                                  --Addison.
      [1913 Webster] -- Un*com"fort*a*ble*ness, n. --
      Un*com"fort*a*bly, adv.
      [1913 Webster]

WordNet (r) 3.0 (2006):

uncomfortableness
    n 1: the state of being tense and feeling pain [syn:
         discomfort, uncomfortableness] [ant: comfort,
         comfortableness]
    2: embarrassment deriving from the feeling that others are
       critically aware of you [syn: self-consciousness,
       uneasiness, uncomfortableness]