(~s)
1.
In Britain, a ~ is a school for children aged between eleven and eighteen.
...Sunderland High School.
N-VAR; N-IN-NAMES
2.
In the United States, a ~ is a school for children usually aged between fourteen and eighteen.
...an 18-year-old inner-city kid who dropped out of ~.
N-VAR; N-IN-NAMES