Physical optics refers to the branch of optics that deals with the study of the nature of light, its properties and its behavior when it interacts with matter. Synonyms for physical optics include geometrical optics, wave optics, and ray optics. Geometrical optics focuses on the geometric aspects of light, while wave optics emphasizes the wave properties of light and its interactions with matter. On the other hand, ray optics emphasizes the behavior of light in terms of rays and is more suitable for simple optical systems that use few optical elements. Despite the differences, all these synonyms refer to the study of light and its properties, and they play a crucial role in various fields of science and engineering.