(~s)
1.
A ~ is an educational course on a particular subject that is run during the summer. The students usually stay at the place where the ~ is being held. (mainly BRIT)
...a ~ for young professional singers.
N-VAR
2.
Summer school is a summer term at a school, college, or university, for example for students who need extra teaching or who want to take extra courses. (mainly AM)
N-VAR