Acronym for rapid application development. A method of building computer systems in which the system is programmed and implemented in segments, rather than waiting until the entire project is completed for implementation. Developed by programmer James Martin, RAD uses such tools as CASE and visual programming. See also CASE, visual programming.

1 radian
2 radius
3 radix

Cool, radical

Unit of absorbed radiation dose, now replaced in the SI system by the gray (one rad equals 0.01 gray), but still commonly used. It is defined as the dose when one kilogram of matter absorbs 0.01 joule of radiation energy (formerly, as the dose when one gram absorbs 100 ergs).
A unit of absorbed ionizing radiation equal to 100 ergs per gram of irradiated material.

Algerian pop music developed in the 1970s from the Bedouin song form melhoun, using synthesizers and electronic drums. Singers often take the name Cheb or Cheba (“young”), for example, Cheb Khaled, Cheb Mami.