Meaning of SECONDARY in English

SECONDARY

(EDUCATION) [adjective] [before noun; not gradable] - relating to the education of children approximately between the ages of 11 and 18 years oldThe proposed reforms include making secondary education compulsory up to the age of 18.Funding has not been equally divided between the primary and secondary phase/level.There has been a drop in the number of children of secondary age.Marcus has just started at secondary school.

Cambridge English vocab.      Кембриджский английский словарь.