noun
same grade; same class
Refers to being in the same school year or class. Often used in compounds such as 同級生 (classmate).
彼は私と同級です。
He is in the same grade as me.
同級生と一緒に勉強した。
I studied together with my classmates.
同級生 specifically means a classmate or someone in the same grade, while 同級 is the abstract concept of being in the same grade.
Compound of 同 (same) and 級 (grade, class).