Re*duc"er (?), n. 1. (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.

2. (Photog.) A reducing agent, either a developer or an agent for reducing density.

Re*du"cer (-s?r), n. One who, or that which, reduces.

Re*duc"er (?), n. 1. (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.

2. (Photog.) A reducing agent, either a developer or an agent for reducing density.