The Collaborative International Dictionary of English v.0.48:

Murk \Murk\, a. [See Murky.]
   Dark; murky.
   [1913 Webster]

         He can not see through the mantle murk.  --J. R. Drake.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Murk \Murk\, n.
   Darkness; mirk. [Archaic] --Shak.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Murk \Murk\, n.
   The refuse of fruit, after the juice has been expressed;
   marc.
   [1913 Webster]

WordNet (r) 3.0 (2006):

murk
    n 1: an atmosphere in which visibility is reduced because of a
         cloud of some substance [syn: fog, fogginess, murk,
         murkiness]
    v 1: make dark, dim, or gloomy