矩形 (jǔ xíng) is a mathematical noun meaning 'rectangle' — a four-sided flat shape with four right angles and opposite sides of equal length. The first character 矩 (jǔ) originally referred to a carpenter’s square, a tool used to check right angles, and carries the idea of precision, measurement, and angular correctness. The second character 形 (xíng) means 'shape' or 'form'. Together, 矩形 literally conveys 'a shape defined by right angles', emphasizing its geometric regularity and structural properties.

This term is used primarily in mathematics, geometry, design, engineering, and everyday descriptions of objects with rectangular features — such as doors, windows, screens, or fields. Unlike more colloquial terms like 长方形 (chángfāngxíng), which emphasizes 'long' and 'square' dimensions, 矩形 is the formal, technical term taught in textbooks and used in academic or professional contexts. It appears frequently in diagrams, instructions, and measurements where accuracy matters.