Meaning of REDUCTION in English

■ noun

1》 the action of reducing.

↘the amount by which something is reduced.

2》 an arrangement of an orchestral score for piano or a smaller group of performers.

3》 a smaller copy of a picture or photograph.

4》 a thick and concentrated liquid or sauce.

Concise Oxford English vocab.      Сжатый оксфордский словарь английского языка.