underclassmann.
Etymology: under- prefix1 3a(a).Previous versions of the OED give the stress as: ˈunderˌclassman.
U.S.society > education > learning > learner > college or university student > [noun] > junior student
1896 F. Cohen & E. Boyd 53 Other much prized delicacies which tantalize the underclassmen as they pass by.
This entry has not yet been fully updated (first published 1921; most recently modified version published online June 2019).