Longman Dictionary of Contemporary English
senior school
noun
EXAMPLES FROM CORPUS
▪ By the time she was in senior school her love of fashion was firmly established.
▪ Kylie progressed from Camberwell's infant section into the senior school and, at least romantically, left Grant behind.
▪ The Elton Report advocates senior school staff carrying out random attendance checks on individual lessons.
▪ Two-thirds had attended a school visit which would have required organisation by senior school management.