cleavage
/ˈkli:vɪdʒ; `klivɪdʒ/ n
1 [C]
(a) split or division 分裂; 分开
(fig 比喻) a deep cleavage within the ruling party 执政党内部严重的分裂.
(b) line along which material such as rock or wood splits （岩石或木等材料的）裂纹.
2 [C, U] (infml 口) hollow between a woman's breasts that can be seen above the low neckline of a dress 乳沟（女子乳房间的凹处, 穿低领连衣裙时所见者）
That new gown shows a large amount of (her) cleavage! 那件新的女长服袒露出（她）大部分乳沟!