'Restrainer' definitions:

Definition of 'restrainer'

(from WordNet)
noun
A chemical that is added to a photographic developer in order to retard development and reduce the amount of fog on a film
noun
A person who directs and restrains [syn: restrainer, controller]

Definition of 'Restrainer'

From: GCIDE
  • Restrainer \Re*strain"er\, n. One who, or that which, restrains. [1913 Webster]