PIE *bhouから、成長する、膨らむ、語源的にはboss, bump, block, embossment, embossment, reliefと同じ。
英語の語源
bosom
bosom: [OE] The immediate source of Old English bōsm was West Germanic *b?sm-, which also produced German busen and Dutch boezem. It has been conjectured that it may come ultimately from Indo-European *bhāghús, which perhaps meant ‘arm’ (source of English bought and possibly bow, as in ‘ship’s bow’); the early occurrence of phrases like ‘in someone’s bosom’ meaning ‘clasped to someone’s chest, in someone’s arms’ may support this. => bough, bow
bosom (n.)
Old English bosm "breast; womb; surface; ship's hold," from West Germanic *bosm- (cognates: Old Frisian bosm, Old Saxon bosom, Middle Dutch boesem, Dutch boezem, Old High German buosam, German Busen "bosom, breast"), perhaps from PIE root *bhou- "to grow, swell," or *bhaghus "arm" (in which case the primary notion would be "enclosure formed by the breast and the arms"). Narrowed meaning "a woman's breasts" is from 1959; but bosomy "big-breasted" is from 1928. Bosom-friend is attested 1580s; bosom buddy from 1920s.
例文
1. The dress exaggerates her wasp waist and enlarges her bosom .
そのワンピースはハチの腰を際立たせ、胸をふっくらさせた。
2.She lay on the bed,her eyes closed and her bosom palpitating.