A "school acquaintance" refers to someone you know from school, but they are not necessarily your close friend. They are more like a person you recognize and may interact with, but you don't have a strong personal connection with them.
Sentences with «school acquaintance»
A high school acquaintance of mine bought his first car with money he made from the stock market. (thecollegeinvestor.com)
They too have family, high school acquaintances and, of course, the long lost friends with whom they need to get in touch. (calbarjournal.com)
The male nurse attending Sally (Margo Martindale) is a resentful high school acquaintance who inherited John's old girlfriend in a marriage that appears to be floundering. (shepherdexpress.com)