secondary school
A somewhat formal or older term for a school providing secondary education, roughly equivalent to middle and high school combined. In modern contexts, 中学校 (junior high) and 高等学校 (senior high) are more common.
In prewar Japan, secondary schools were often separated for boys and girls.
彼は地元の中等学校を卒業後、都会の大学に進学した。
After graduating from a local secondary school, he went on to a university in the city.