- angstrom, angstrom unit, A - a metric unit of length equal to one ten billionth of a meter (or 0.0001 micron); used to specify wavelengths of electromagnetic radiation
--1 is a kind of metric linear unit
--1 is a part of
--1 has parts: picometer, picometre, micromicronnanometer, nanometre, nm, millimicron, micromillimeter, micromillimetre