口こう吟ぎん

noun, noun or participle which takes 'suru'

humming to oneself

Refers to quietly humming a tune under one's breath, often while doing something else. Can be used as a noun or with する.

• 彼かれは仕し事ごとをしながら口こう吟ぎんをしている。

  He hums to himself while working.

• 口こう吟ぎんで好すきな曲きょくを口くちずさむ。

  I hum my favorite song under my breath.