reducer

noun

1. Something that reduces.

2. chemistryA reducing agent.

3. hydraulicsA 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 machine.

4. photographyA liquid used in the process of developing a negative to reduce its darkness.

5. plumbingA component used to connect two pipes of different bores.

6. softwareA function that takes state and action as arguments and returns the next state of the app.

7. association footballThe reduction of the contribution to a football game of a more talented opponent by intimidation using a brutal tackle.

8. 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

   Similar: reducing agent, reductant

9. Pipefitting that joins two pipes of different diameter