Curvilinear refers to shapes or lines that are curved rather than straight. This term is often used in mathematics, art, and design to describe forms that flow smoothly and create a sense of movement. Curvilinear designs can be found in nature, such as the shapes of rivers or the contours of hills. In architecture, curvilinear elements can add visual interest and softness to structures. Buildings with curvilinear features often stand out due to their unique and organic appearance, contrasting with more rigid, angular designs. Examples include the works of Frank Lloyd Wright and Zaha Hadid, who incorporated curves into their architectural styles.