reduction-n; 2 Senses

Sense Number 1: decreasing

Commentary: REDUCTION[+event] The act of becoming smaller, lower, less important, less complex, etc. Can occur with or without an agent.

The reduction of voting age to eighteen was supposed to have caused politicians to pay attention to young people.
The reduction of resolution to 200 x 600 might make your image a little unclear.
John's reduction of the complex political situation to a simple "us against them" viewpoint won him the election.
Unfortunately, the last few days has seen a major price reduction for several stocks.

WordNet 2.0 Sense Numbers: 1 3

Sense Number 2: electron transfer

Commentary: REDUCTION[+event] Probably a rare sense. The gaining of an electron by an atom. The opposite of oxidation.

My teacher gave me a set of oxidation-reduction reaction problems for homework.
The element that gained electrons was said to have undergone reduction.

WordNet 2.0 Sense Numbers: 2