national anthem
Refers to the official song of a country, such as 君が代 for Japan.
オリンピックの開会式で国歌が流れた。
The national anthem was played at the Olympic opening ceremony.
We sang the national anthem at the opening ceremony.
日本の国歌は「君が代」です。
Japan's national anthem is 'Kimigayo'.
選手たちは起立して国歌を斉唱した。
The athletes stood and sang the national anthem together.
The national anthem played at the ceremony hall.
国旗 is the national flag while 国歌 is the national anthem, and the two are often taught together so learners may mix them up.
校歌 is a school song sung at school events, whereas 国歌 is a country's official anthem, and the shared 歌 makes them easy to confuse.
国歌 is counted with 首 as it is a song or poem, e.g. 国歌一首.
Compound of 国 (country) and 歌 (song). The reading こっか is a regular on'yomi combination.