1. 1. Small: microcircuit.
   2. Abnormally small: microcephaly.
   3. Requiring or involving microscopy: microsurgery.
2. One-millionth (10 ^-6): microampere.

[Greek mīkro-, from mīkros, small.]

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.