refers to the most sexually-attractive star-actresses of an era, who would be popularized in seductive poses usually semi-clad - in pictures, calendars, or mass-produced posters that were usually literally
"pinned-up", usually with thumbtacks, on bedroom walls, the insides of lockers,
and so forth; this practice started especially amongst GI servicemen away from home during military combat who pined for the girl-back-home'; related terms
are cover girl (for magazine covers), model or cheesecake
Pin-up girl of all pin-up girls, Betty Grable was the favorite among US soldiers during World War II. Starting chorus girl when she was barely a teenager, Betty proved to be a gifted singer, dancer and actress. She made over 40 films during her career, including "How To Marry A Millionaire" with Marilyn Monroe and Lauren Bacall. Long before Mary Hart, Betty's legs were insured with Lloyds of London for a reputed $1 million. During her heyday, Betty was both the highest paid star in Hollywood and one of the wealthiest women in all of America.
Rita Hayworth was one of the most popular pin-up queens of World War II. Second only to Betty Grable, who was also number 1 at the box office. It may not have been an image Rita particularly relished, but when the war came along, there was no stopping GI's coast to coast and all over the world from plastering Rita's image on everything from barracks walls to bombers planes.
This was the most famous Hayworth pin-up picture. It was taken by Bob Landry and first appeared in a 1941 issue of Life magazine. It proceeded to become one of the most instantly recognizable pictures ever taken. Helen Gurley Brown, Editor-In-Chief of Cosmopolitan said of the picture "I never saw a better 'girl' picture, and that includes about a million from Cosmopolitan!"