word requests - Does 同級生 mean "classmate" instead of "batchmate" despite the meanings of the individual kanji?

I was looking for the word "batchmate" (entered the same year as you/in the same school grade, i.e. in between 先輩 and 後輩), and found some answers (1,2) on this site that gives 同級生 as a translation to "classmate". Can this word also be used for students not in the same class but in the same grade? For example, students in a club of the same grade but in different classes.

For context, the sentence I am trying to build is

先輩にも、＿＿にも、後輩までも笑われた。

I was laughed at by my seniors, my batchmates, and even by my juniors.

This is in context of club activities.

The answers on this site linked above translate 同級生 as "classmate", and so do some Japanese-English dictionaries. That surprised me because of how breaking up the kanji would literally give "same-grade-students". Can 同級生 also be used in the example above?

Or... does the Japanese concept of "classmates" extend beyond classes and include everyone in the same grade? I have no idea.

Answer

Yes 同級生 can mean both "people in the same class" and "people in the same grade (and in the same school)" depending on the context. 大辞泉 says:

どうきゅう‐せい〔ドウキフ‐〕【同級生】

同じ学級の生徒・学生。同じ学年の生徒・学生。

先輩, 後輩, 下級生 and 上級生 always mean students in different grades. When 同級生 is used in contrast with them, like in your example, 同級生 safely means 同じ学年.

In addition, 同級生 tends to mean 同じ学年 if a long time has passed after graduating from the school. Most schools shuffle the members of classes every school year, and who belonged to which class in one specific grade will become less important when you reach, say, 30. If someone in his thirties said 彼女は高校で同級生でした, I would interpret it just means she belonged to the same school and was in the same grade.

If you need to avoid confusion, you can always say 彼は同じクラスだった or 彼は同じ学年だった instead of 彼は同級生だった. クラスメート always refers to people in the same class, too.