Lucite is a term for plastic. Specifically, it was DuPont's name for an acrylic resin that they developed, which when molded into a purse, can create some stunning accessories - works of art really!
Lucite purses were very popular in the 1950s, and over at Collector's Weekly, there is a fantastic write up about these gorgeous handbags. I encourage you to read the article and drool over the beautiful bags! All images courtesy of Collector's Weekly.