The Collaborative International Dictionary of English v.0.48:
Moistener \Mois"ten*er\, n. One who, or that which, moistens. --Johnson. [1913 Webster]WordNet (r) 3.0 (2006):
moistener n 1: a device that dampens or moistens something; "he used a dampener to moisten the shirts before he ironed them" [syn: dampener, moistener]