Definition of blueprint

The word "blueprint" originates from the early 20th century. In the late 1800s, a process called cyanotype was developed to create photographs using a solution of potassium ferricyanide and ferric ammonium citrate. This solution turned sunlight-blue, and thus, the resulting images were also blue. Architects, engineers, and other professionals began using this process to create copies of their designs, drawings, and plans. To differentiate them from regular prints, they started calling these blue-tinged copies "blueprints." The term gained widespread use, and by the mid-20th century, it was commonly used to refer to any detailed plan or diagram, regardless of whether it was created using the original cyanotype process or not. Today, the term "blueprint" is still widely used in various industries, including architecture, engineering, and business.