'Softener' definitions:

Definition of 'softener'

From: WordNet
noun
A substance added to another to make it less hard

Definition of 'Softener'

From: GCIDE
  • Softener \Sof"ten*er\, n. One who, or that which, softens. [Written also, less properly, softner.] [1913 Webster] [1913 Webster]