gamma rays pl. n. electromagnetic radiation of wavelengths shorter than X-rays, given off by certain radioactive substances. Gamma rays used in nuclear medicine have higher energy than diagnostic X-rays and greater penetration; higher doses are used in radiotherapy. Gamma rays are harmful to living tissues and can be used to sterilize certain materials and to kill bacteria as a means of food preservation.

gamma rays Electromagnetic radiation, about 10⁻¹⁰ to 10⁻¹⁴ m in wavelength, similar to, but of shorter wavelength than X-rays, which is emitted by radioactive substances.

gamma rays Electromagnetic radiation, about 10⁻¹⁰ to 10⁻¹⁴m in wavelength, similar to, but of shorter wavelength than X-rays, emitted by radioactive substances.