Pronunciation: (mī'kron),[key] —n., —pl.-crons, -craPronunciation: (-kru).[key] 1. Also called micrometer. the millionth part of a meter. Symbol: μ, mu
2. Physical Chem.a colloidal particle whose diameter is between 0.2 and 10 microns.
3. Physics.a very small unit of pressure, equal to that exerted by a column of mercury 1μ high. Also,mikron.