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[ther-mom-i-ter] /θərˈmɒm ɪ tər/
an instrument for measuring temperature, often a sealed glass tube that contains a column of liquid, as mercury, that expands and contracts, or rises and falls, with temperature changes, the temperature being read where the top of the column coincides with a calibrated scale marked on the tube or its frame.
Origin of thermometer
First recorded in 1615-25; thermo- + -meter
Related forms
[thur-muh-me-trik] /ˌθɜr məˈmɛ trɪk/ (Show IPA),
thermometrical, adjective
thermometrically, adverb Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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British Dictionary definitions for thermometer


an instrument used to measure temperature, esp one in which a thin column of liquid, such as mercury, expands and contracts within a graduated sealed tube See also clinical thermometer, gas thermometer, resistance thermometer, thermocouple, pyrometer
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
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Word Origin and History for thermometer

1630s, from French thermomètre (1620s), coined by Jesuit Father Leuréchon from Greek thermos "hot" (see thermal) + metron "measure" (see -meter). An earlier, Latinate form was thermoscopium (1610s). The earliest such device was Galileo's air-thermometer, invented c.1597.

Online Etymology Dictionary, © 2010 Douglas Harper
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thermometer in Medicine

thermometer ther·mom·e·ter (thər-mŏm'ĭ-tər)
An instrument for measuring temperature.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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thermometer in Science
An instrument used to measure temperature. There are many types of thermometers; the most common consist of a closed, graduated glass tube in which a liquid expands or contracts as the temperature increases or decreases. Other types of thermometers work by detecting changes in the volume or pressure of an enclosed gas or by registering thermoelectric changes in a conductor (such as a thermistor or thermocouple).
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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