The Collaborative International Dictionary of English v.0.48:

Freck \Freck\, v. t. [Cf. Freak, v. t., Freckle.]
   To checker; to diversify. [R. & Poet.]
   [1913 Webster]

         The painted windows, frecking gloom with glow.
                                                  --Lowell.
   [1913 Webster]