A pin-up model is a model whose mass-produced pictures see widespread appeal as part of popular culture. Pin-up models were variously glamour models, fashion models, or actresses. Pin-ups are intended for informal display, i.e. meant to be "pinned-up" on a wall, which is the basis for the etymology of the phrase. These pictures are also sometimes known as cheesecake photos. Cheesecake was an American slang word that became a publicly acceptable term for scantily-clad, semi-nude, or nude photos of women because pin-up was considered taboo in the early 20th century.
