Cleavage

The cleavage be the area between a woman's breasts, especially when revealed by a low-cut neckline.

When possessing Rose Tyler's body, Cassandra O'Brien.Δ17 unbuttoned her shirt and exposed her cleavage in an attempt to make herself appear more desirable. She also took visible pleasure in concealing a sleep-inducing perfume down Rose's décolletage. (TV: New Earth)

Grace Holloway's cleavage was shown when wearing her opera dress. (TV: Doctor Who)

Gwen Cooper's cleavage was shown when she made out with Carys Fletcher under the pheromone control of the gas. (TV: Day One)

Melody Malone's cleavage "could fell an ox at twenty feet", according to Melody Malone: Private Detective in Old New York Town. (TV: The Angels Take Manhattan)