noun
very small breasts; flat chest
Colloquial and often used in casual or humorous contexts. Compare with 微乳 (びにゅう), which is a more neutral term for small breasts.
See also: 微乳
彼女はない乳を気にしている。
She is self-conscious about her very small breasts.
ネットで「ない乳」って検索したら、いろんな情報が出てきた。
When I searched for 'naichichi' online, all sorts of information came up.
微乳 is a more neutral, descriptive term for small breasts, while ない乳 is colloquial and can carry a humorous or self-deprecating tone.
貧乳 literally means 'poor breasts' and is a common slang term for small breasts, often used in anime/manga contexts. ない乳 is more direct and emphatic about the lack of size.
Compound of ない (nai, 'not exist') and 乳 (chichi, 'breasts'), literally 'no breasts'. The exact origin is uncertain, but it likely arose as internet slang or colloquial expression.