Homonym: reduction (Decrease)
Reduction is a process in chemistry where a substance gains electrons or decreases its oxidation state. This often occurs during chemical reactions, such as when a metal ion is converted to its elemental form. For example, in the reaction of copper(II) oxide with hydrogen, the copper ion is reduced to copper metal.
In a broader context, reduction can also refer to the act of making something smaller or less in amount, degree, or size. This can apply to various fields, such as mathematics, where a complex problem is simplified, or in environmental science, where efforts are made to reduce waste and pollution.