I know the word upperclassman but it means a junior or senior student in an American high school, college, or university. If I was a freshman I cannot call a sophomore an upperclassman. What the word should mean: to not only be a junior or senior student but a student with any higher grade. What's worse, there is no a word like upperclasswoman for a female student (this is an additional reason why upperclassman wouldn't work for me).
In China there are two words: 学长 and 学姐 referring to any students with a higher grade; the former is for male students and the latter for female ones. All of the following sayings are very normal:
Hello 学长, she's one of my 学姐.
Hey, 学长/学姐, can you tell me how to get to the cafeteria?
I'm her/his 学长.
These two words can refer to any students with a higher grade, no matter student in middle school, or university. Sometimes we just don't want/need to know his/her grade. For instance, as a freshman in the new students enrolling day I would address the majority male students on campus as 学长 in situations like this: Hey, 学长, can you tell me how to get to the cafeteria?
I wonder if there exists such an equivalent one/two words in English, barring upperclassman.