/muy"kron/ , n. , pl. microns, micra /-kreuh/ .
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 .
[ 1880-85; mikrón a little, n. use of neut. sing. of mikrós small; see -ON 1 ]