Longman Dictionary of Contemporary English
school friend
noun
EXAMPLES FROM CORPUS
▪ He phoned an old school friend named Andy Rourke.
▪ I share digs with an old school friend of mine, Daphne Harcourt-Browne.
▪ She was an old school friend, although we were out of school by then.
▪ There she was able to board with the family of an old school friend.
▪ Various willing hands, including her school friend Balie Waggener joined in the project.