The term "clean lines" refers to a style in design and architecture that emphasizes simplicity, minimalism, and geometric forms. It means having an uncluttered appearance with smooth, straight edges and clear, well-defined shapes. In other words, it is about creating a sense of order, balance, and harmony through the use of straightforward lines and curves. The goal is to create a visually pleasing design that is both functional and aesthetically appealing, without any unnecessary embellishments or distractions.