noun
saggy breasts; drooping breasts
Slang term for breasts that hang down, often used in casual or vulgar contexts.
彼女は垂れ乳がコンプレックスだと言っていた。
She said she has a complex about her saggy breasts.
Compound of 垂れ (tare, 'hanging down') and 乳 (chi, 'breasts'). The exact origin is uncertain, but it is a straightforward descriptive term.