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radioman one who operates or repairs radio equipment.
radiometer an instrument for measuring radiant energy or transforming radiant energy into mechanical energy, consisting of vertical vanes that absorb more heat on one side than the other, so that they rotate around an axis when irradiated.
radiopaque of a substance, resistant to penetration by radiation such as x-rays or gamma rays.
radiophone a telephone whose sound is transmitted by radio waves; radiotelephone.
radiophoto radiophotograph.
radiophotograph a photograph or other visual image transmitted by radio.
radioscopy the internal examination of opaque objects by means of radiation such as x-rays.
radiosensitive sensitive or susceptible to destruction by radiant energy, as living organisms or tissue.
radiosonde an airborne meteorological instrument that radios information about air temperature, pressure, and humidity to ground stations; radiometeorograph.
radio spectrum the portion of the electromagnetic spectrum consisting of radio waves, esp. those most frequently used in radio and television broadcasting, from ten kilohertz to 300 gigahertz.
radio station an organization equipped for broadcasting radio. [2 definitions]
radiotelegraph a telegraph in which signals are transmitted by radio rather than by wires.
radiotelegraphy the design, construction, or operation of telegraphs whose signals are transmitted by radio waves.
radiotelephone a telephone whose sound is transmitted by radio waves; radiophone.
radio telescope a concave reflector or array of reflectors designed to collect and focus extraterrestrial radio waves for analysis.
radiotherapy the treatment of an illness with radioactive substances or x-rays.
radio wave an electromagnetic wave with a wavelength of between one millimeter and thirty thousand meters, or a frequency of between ten kilohertz and three hundred thousand megahertz.
radish one of a group of herbs of the cabbage family that have a pungently flavored, crisp, edible root. [2 definitions]
radium a radioactive chemical element that has eighty-eight protons in each nucleus and that occurs in pure form as a solid metal, used esp. as a radiation source for cancer treatment. (symbol: Ra)
radium therapy the treatment of disease, esp. cancer, by means of radium.
radius a straight line segment extending from the center to the surface of a sphere or from the center to the circumference of a circle. [7 definitions]