'Reducer' definitions:

Definition of 'reducer'

(from WordNet)
noun
A substance capable of bringing about the reduction of another substance as it itself is oxidized; used in photography to lessen the density of a negative or print by oxidizing some of the loose silver [syn: reducing agent, reducer, reductant]
noun
Pipefitting that joins two pipes of different diameter

Definition of 'Reducer'

From: GCIDE
  • Reducer \Re*du"cer\ (-s?r), n.
  • 1. One who, or that which, reduces. [1913 Webster]
  • 2. (Mach.) (a) A contrivance for reducing the dimensions of one part so as to fit it to another, as a reducing coupling, or a device for holding a drilling a chuck. (b) A reducing motion. (c) A reducing valve. (d) A hydraulic device for reducing pressure and hence increasing movement, used to transmit the load from the hydraulic support of the lower shackle to the lever weighing apparatus in some kinds of heavy testing machines. [Webster 1913 Suppl.]
  • 3. (Photog.) A reducing agent, either a developer or an agent for reducing density. [Webster 1913 Suppl.]
  • 4. (Chem.) a reducing agent. [PJC]