secondary education

high-school education, knowledge that is accumulated by the end of one's years in high-school, twelve years of education

Secondary education is the final stage of compulsory education, preceded by primary education and followed by higher education. It is characterised by transition from the typically compulsory, comprehensive primary education for minors to the optional, selective tertiary, "post-secondary", or "higher" education (e.g., university, vocational school) for adults. Depending on the system, schools for this period or a part of it may be called secondary schools, high schools, gymnasiums, lyceums, middle schools, colleges, vocational schools and preparatory schools, and the exact meaning of any of these varies between the systems.
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Noun
1. education beyond the elementary grades; provided by a high school or college preparatory school
(hypernym) education, instruction, teaching, pedagogy, educational activity