from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A device for measuring very small distances, objects, or angles, especially one based on the rotation of a finely threaded screw, as in relation to a microscope.
- n. A unit of length equal to one thousandth (10-3) of a millimeter or one millionth (10-6)of a meter.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. An SI/MKS unit of measure, the length of one one-millionth of a meter. Symbols: µm, um, rm
- n. A device used to measure distance very precisely but within a limited range, especially depth, thickness, and diameter.
from the GNU version of the Collaborative International Dictionary of English
- n. An instrument, used with a telescope or microscope, for measuring minute distances, or the apparent diameters of objects which subtend minute angles. The measurement given directly is that of the image of the object formed at the focus of the object glass.
from The Century Dictionary and Cyclopedia
- n. An instrument for measuring microscopic lengths and angles.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. a metric unit of length equal to one millionth of a meter
- n. caliper for measuring small distances
micro- + meter (Wiktionary)
From French micrometre (Wiktionary)