Historically and even today in popular vocabulary "Reduction" is a chemical reaction where an oxygene link is removed. The correct chemical context defines reduction as a processes which adds electrons to an atom or molecule. A second partner (atom or molecule) provides the electrons for this reaction.

Oxygen is able to provide one or two electrons in a chemical reaction.

As a reduction process is allways related to an oxidation it is usual to use the designation Redox (Reduction - Oxydation)