Source : Webster's Revised Unabridged Dictionary (1913)

Sunless \Sun"less\, a.
   Destitute or deprived of the sun or its rays; shaded;
   shadowed.

         The sunken glen whose sunless shrubs must weep.
                                                  --Byron.

Source : WordNet®

sunless
     adj : filled or abounding with clouds [syn: {cloud-covered}, {clouded},
            {overcast}]