Source : Webster's Revised Unabridged Dictionary (1913)

Overcloud \O`ver*cloud"\, v. t.
   To cover or overspread with clouds; to becloud; to overcast.

Source : WordNet®

overcloud
     v 1: become covered with clouds; "The sky clouded over" [syn: {cloud
          over}, {cloud up}]
     2: make obscure or unclear; "The distinction was obscured"
        [syn: {obscure}, {bedim}]