ultramicrometer

ul·tra·mi·crom·e·ter

 (ŭl′trə-mī-krŏm′ĭ-tər)
n.
An extremely accurate micrometer.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

ultramicrometer

(ˌʌltrəmaɪˈkrɒmɪtə)
n
1. (General Physics) a micrometer for measuring extremely small distances
2. (Tools) a micrometer for measuring extremely small distances
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
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