A Palladian window is a large window that is divided into three parts. The center section is larger than the two side sections, and is usually arched. Renaissance architecture and other buildings in classical styles often have Palladian windows. On Adam or Federal style houses, there is often a Palladian window in the center of the second story.
The term "Palladian" comes from Andrea Palladio, a Renaissance architect whose work inspired some of the greatest buildings in Europe and the United States. Modeled after classical Greek and Roman forms, Palladio's buildings often featured arched openings.