An underclassman is a student in the first or second year of a four-year American high school or college — a freshman or a sophomore. The opposite is 'upperclassman', a junior or senior. This word belongs to American school life and you will hear it in American films, campus talk and school newspapers; British schools do not use it at all, and Taiwanese students will not meet it in a British exam. Notice the flavour: it is not an insult, but it does carry a small hint of being the younger, less experienced group — the ones who do not yet know where things are, who get teased a little by the older students. That social feeling is really the point of having the word. The '-man' ending is used for students of any gender in traditional usage, but that now feels dated to many people, and American schools increasingly write 'underclass students', 'first- and second-year students', or 'underclassmen' only when speaking loosely. The plural is 'underclassmen'. Be careful with the '-man' pattern: 'freshman' and 'sophomore' name one year each, while 'underclassman' covers both.

（美國高中或大學的）低年級生，指一、二年級學生。台灣說「學弟妹」的那個位置，但這個字只講年級、不含台灣學長學姊制的階級意味。