Wiktionary
n. A young woman wearing a tight sweater that emphasizes the bustline: a popular Hollywood fashion of the 1940s and 1950s.
WordNet
n. a girl with an attractive bust who wears tight sweaters
Wikipedia
The term Sweater girl was made popular in the 1940s and 1950s to describe Hollywood actresses like Lana Turner, Jayne Mansfield, and Jane Russell, who adopted the popular fashion of wearing tight sweaters over a cone- or bullet-shaped bra that emphasized the woman's bustline. The term was virtually synonymous with " pin-up girl," a popular culture trope of the Second World War referring to the pretty girls whose pictures adorned soldiers' barracks.
The sweater girl trend was not confined to Hollywood and was viewed with alarm by some. In 1949 a Pittsburgh police superintendent even singled out the sweater girl as a symptom of the moral decline of postwar youth:
Sweater Girl a 1942 American film written by Robert Blees and Beulah Marie Dix, directed by William Clemens and starring Eddie Bracken, June Preisser, Phillip Terry, and Betty Jane Rhodes. It was released on July 13, 1942.
Sweater Girl marked the debut of the classic World War II-era wartime song, " I Don't Want To Walk Without You". The song was performed on screen by actress Betty Jane Rhodes.
Usage examples of "sweater girl".
If a new Sweater Girl every month, why not an Udders Day, for the suitable honouring of all mammals?
And what red-blooded American boy will look twice at a Geography whiz with scabs on her knees, when he could have a Sweater Girl?
And in the voice of the imagined black-sweater girl Iris assured him that Ike would be with him in just a moment.