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ultramicrometer

American  
[uhl-truh-mahy-krom-i-ter] / ˌʌl trə maɪˈkrɒm ɪ tər /

noun

  1. a micrometer calibrated to a very fine scale and capable of measuring extremely small magnitudes.


ultramicrometer British  
/ ˌʌltrəmaɪˈkrɒmɪtə /

noun

  1. a micrometer for measuring extremely small distances

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Etymology

Origin of ultramicrometer

First recorded in 1925–30; ultra- + micrometer 1