partially exposed breasts; breasts bulging out of clothing
Slang term describing breasts that are not fully covered by clothing, often due to a low-cut top or loose garment. Used in casual, often male-oriented conversation.
Her dress almost revealed a bit of underboob.
That gravure idol's sideboob is amazing.
Standard kanji-kana mixed spelling; the most common written form.
Kanji spelling using 食み (to protrude); less common but attested.
Katakana-mixed spelling; sometimes used for stylistic emphasis.
Full katakana spelling; used in casual or emphatic contexts.
From はみ出る (to protrude) + 乳 (breast). The exact origin is uncertain, but it likely emerged in colloquial speech to describe the visual effect of breasts spilling out of clothing.