A unit of measurement of length equal to one hundred-millionth of a centimeter (or 0.0000000001 meter), used especially to measure the wavelengths of visible light and of other forms of electromagnetic radiation, such as ultraviolet radiation and X-rays. Visible light covers the range from violet at 4,000 to red at about 7,000 angstroms. Scientists now prefer to use the nanometer (nm); 1 nm = 10 ?. In everyday terms, a sheet of paper is approximately 1,000,000 angstroms thick. It is named after Anders Jonas ?ngstr?m (1814-1874), the Swedish physicist and astronomer who founded the science of spectroscopy and discovered by studying the solar spectrum that there is hydrogen in the sun's atmosphere. Electromagnetic radiation travels in waves. Abbreviated ?.(pr. ANG-strəm or AHNG-strəmAlso see color. angstrom