The chemical process of reduction, is any process in which electrons are added to an atom or ion (as by removing oxygen or adding hydrogen); always occurs accompanied by oxidation of the reducing agent.
To allow a sauce or stock to simmer without a lid on. This makes it thicker.This is another answer for cooking .
The property which opposes the establishment of the magnetic flux in the magnetic circuits is known as reductance. it is analogous to the resistance in electric circuit.
Reduction is to reduce, lessen or decrease in size or amount.
Reductal