1UKA student organization present in many colleges, universities, and high schools. In higher education, the students' union is often accorded its own building on the campus, dedicated to social, organizational activities, and representation.
2UKThe building where the union provides such services.
3UKA student organization to provide services to students, especially of higher education (in this sense only US English, and then almost always "student union")
4UKThe building where the union provides such services. (in this sense only US English, and then almost always "student union")