also: ちちみぞ
noun
mammary slit
Zoological term for the groove housing the mammary glands in whales, dolphins, and porpoises.
クジラの乳溝は、乳腺を保護する役割がある。
The mammary slit of whales serves to protect the mammary glands.
noun
Slang term for the cleavage between breasts; often written in kana as ちちみぞ.
そのドレスはちちみぞが強調されるデザインだ。
That dress has a design that emphasizes the cleavage.
Compound of 乳 (chichi, 'milk; breast') and 溝 (mizo, 'groove; furrow'). The reading にゅうこう uses the on'yomi of both characters.