Source : Webster's Revised Unabridged Dictionary (1913)

Clouding \Cloud"ing\, n.
   1. A mottled appearance given to ribbons and silks in the
      process of dyeing.

   2. A diversity of colors in yarn, recurring at regular
      intervals. --Knight.

Cloud \Cloud\, v. t. [imp. & p. p. {Clouded}; p. pr. & vb. n.
   {Clouding}.]
   1. To overspread or hide with a cloud or clouds; as, the sky
      is clouded.

   2. To darken or obscure, as if by hiding or enveloping with a
      cloud; hence, to render gloomy or sullen.

            One day too late, I fear me, noble lord, Hath
            clouded all thy happy days on earth.  --Shak.

            Be not disheartened, then, nor cloud those looks.
                                                  --Milton.

            Nothing clouds men's minds and impairs their honesty
            like prejudice.                       --M. Arnold.

   3. To blacken; to sully; to stain; to tarnish; to damage; --
      esp. used of reputation or character.

            I would not be a stander-by to hear My sovereign
            mistress clouded so, without My present vengeance
            taken.                                --Shak.

   4. To mark with, or darken in, veins or sports; to variegate
      with colors; as, to cloud yarn.

            And the nice conduct of a clouded cane. --Pope.

Source : WordNet®

clouding
     n : the process whereby water particles become visible in the
         sky [syn: {clouding up}]