Source : Webster's Revised Unabridged Dictionary (1913)

Dew \Dew\, n. [AS. de['a]w; akin to D. dauw, G. thau, tau, Icel.
   d["o]gg, Sw. dagg, Dan. dug; cf. Skr. dhav, dh[=a]v, to flow.
   ???. Cf. {Dag} dew.]
   1. Moisture from the atmosphere condensed by cool bodies upon
      their surfaces, particularly at night.

            Her tears fell with the dews at even. --Tennyson.

   2. Figuratively, anything which falls lightly and in a
      refreshing manner. ``The golden dew of sleep.'' --Shak.

   3. An emblem of morning, or fresh vigor. ``The dew of his
      youth.'' --Longfellow.

   Note: Dew is used in combination; as, dew-bespangled,
         dew-drenched, dewdrop, etc.

Dew \Dew\, v. t. [imp. & p. p. {Dewed}; p. pr. & vb. n.
   {Dewing}.]
   To wet with dew or as with dew; to bedew; to moisten; as with
   dew.

         The grasses grew A little ranker since they dewed them
         so.                                      --A. B.
                                                  Saxton.

Dew \Dew\, a. & n.
   Same as {Due}, or {Duty}. [Obs.] --Spenser.

Source : WordNet®

dew
     n : water that has condensed on a cool surface overnight from
         water vapor in the air; "in the morning the grass was wet
         with dew"