unit of length used chiefly in measuring wavelengths of light, equal to 10⁻¹⁰ metre, or 0.1 nanometer. It is named for the 19th-century Swedish physicist Anders Jonas Ångström (Ångström, Anders Jonas). The angstrom and multiples of it, the micron (10⁴ Å) and the millimicron (10 Å), are also used to measure such quantities as molecular diameters and the thickness of films on liquids.