Source : Webster's Revised Unabridged Dictionary (1913)

Dimness \Dim"ness\, n. [AS. dimness.]
   1. The state or quality ? being dim; lack of brightness,
      clearness, or distinctness; dullness; obscurity.

   2. Dullness, or want of clearness, of vision or of
      intellectual perception. --Dr. H. More.

   Syn: Darkness; obscurity; gloom. See {Darkness}.

Source : WordNet®

dimness
     n 1: the state of being poorly illuminated [syn: {duskiness}]
     2: the property of lacking brilliance [syn: {subduedness}]
     3: the quality of being dim [syn: {faintness}]