The Collaborative International Dictionary of English v.0.48:

Pathos \Pa"thos\ (p[=a]"th[o^]s), n. [L., from Gr. pa`qos a
   suffering, passion, fr. paqei^n, pas`chein, to suffer; cf.
   po`nos toil, L. pati to suffer, E. patient.]
   That quality or property of anything which touches the
   feelings or excites emotions and passions, esp., that which
   awakens tender emotions, such as pity, sorrow, and the like;
   contagious warmth of feeling, action, or expression; pathetic
   quality; as, the pathos of a picture, of a poem, or of a cry.
   [1913 Webster]

         The combination of incident, and the pathos of
         catastrophe.                             --T. Warton.
   [1913 Webster]

   1. The quality or character of those emotions, traits, or
      experiences which are personal, and therefore restricted
      and evanescent; transitory and idiosyncratic dispositions
      or feelings as distinguished from those which are
      universal and deep-seated in character; -- opposed to
      ethos.
      [Webster 1913 Suppl.]

   2. Suffering; the enduring of active stress or affliction.
      [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

pathos
    n 1: a quality that arouses emotions (especially pity or
         sorrow); "the film captured all the pathos of their
         situation" [syn: pathos, poignancy]
    2: a feeling of sympathy and sorrow for the misfortunes of
       others; "the blind are too often objects of pity" [syn:
       commiseration, pity, ruth, pathos]
    3: a style that has the power to evoke feelings