Meaning of DERATE in English

(ˈ)dē+ transitive verb

Etymology: de- + rate

1. : to reduce or eliminate rates on

the Local Government Act of 1929 derated British agricultural holdings

2. : to lower the rated capability of (electrical apparatus) because of deterioration, inadequacy, age, or obsolescence

Webster's New International English Dictionary.      Новый международный словарь английского языка Webster.