noun
double circle; excellent mark
Used in school grading to indicate 'very good' or 'excellent', often alongside ○ (circle) and △ (triangle).
先生がテストに二重丸をくれた。
The teacher gave me a double circle on the test.
この問題は全問正解だったので、二重丸をもらった。
I got a double circle because I answered all the questions correctly.
Compound of 二重 (にじゅう, 'double') and 丸 (まる, 'circle'). The symbol ◎ is a direct representation of the double circle.