class or grade / generation / plaintiff and defendant (old) / government department (old)
曹
=
一
+
曰
+
曲
:
Mnemonic symbol: a Chinese / white herring.
The King of Chu (c) called Cao Cao too often (曹) and now he's about to enter the aorta (ao2). To pay him respect the King of Chu plays a flute (一) and the Chinese / white herring (曹) plays a harp (曲). They also record their performance with a microphone (曰).