In physics, scattering is a wide range of physical processes where moving particles or radiation of some form, such as light or sound, are forced to deviate from a straight trajectory by localized non-uniformities in the medium through which they pass. In conventional use, this also includes deviation of reflected radiation from the angle predicted by the law of reflection. Reflections of radiation that undergo scattering are often called diffuse reflections and unscattered reflections are called specular (mirror-like) reflections. Originally, the term was confined to light scattering. As more "ray"-like phenomena were discovered, the idea of scattering was extended to them, so that William Herschel could refer to the scattering of "heat rays" in 1800. John Tyndall, a pioneer in light scattering research, noted the connection between light scattering and acoustic scattering in the 1870s. Near the end of the 19th century, the scattering of cathode rays and X-rays was observed and discussed. With the discovery of subatomic particles and the development of quantum theory in the 20th century, the sense of the term became broader as it was recognized that the same mathematical frameworks used in light scattering could be applied to many other phenomena.

சிதறிய கதிர்வீச்சு என்பது மருத்துவத்திற்காகவும் கதிர் படம் எடுக்கும் போதும் முதன்மைக் கதிர்வீச்சானது நோயாளி அல்லது பிற பொருட்களின் மீது விழும் போது அவை சிதறடிக்கப்பட்டு எல்லாத் திசைகளிலும் கதிர்கள் சிதறுவதைக் குறிக்கிறது. இவ்வாறு சிதறும் கதிர்வீச்சின் ஆற்றல் முதன்மைக் கதிர்வீச்சின் ஒரு விழுக்காடுதான் என்றாலும் இதனைக் கட்டுப்படுத்த வேண்டுவது மிகவும் அவசியமானதாகும்.