Source : Webster's Revised Unabridged Dictionary (1913)

Moisten \Mois"ten\, v. t. [imp. & p. p. {Moistened}; p. pr. &
   vb. n. {Moistening}.]
   1. To make damp; to wet in a small degree.

            A pipe a little moistened on the inside. --Bacon.

   2. To soften by making moist; to make tender.

            It moistened not his executioner's heart with any
            pity.                                 --Fuller.

Source : WordNet®

moistening
     n : the act of making something slightly wet [syn: {dampening}]