thermometer

American  

[ther-mom-i-ter] / θərˈmɒm ɪ tər /

noun

• thermometers
  plural

1. 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.

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thermometer British  

/ θəˈmɒmɪtə /

noun

1. 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

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thermometer Scientific  

/ thər-mŏm′ĭ-tər /

1. 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).

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Other Word Forms

Derived Forms

• thermometric
  adjective
• thermometrical
  adjective
• thermometrically
  adverb

Inflected Forms

Nouns

• thermometers
  plural

Etymology

Origin of thermometer

First recorded in 1615–25; thermo- + -meter

Explanation

A thermometer is a tool that measures temperature — how hot or cold something is. Thermometers are used to see if you have a fever or tell you how cold it is outside. Made up of thermo (heat) and meter (measuring device), the meaning of the word thermometer is pretty straightforward. Thermometers measure temperatures in degrees, according to either the Celsius or Fahrenheit system. Meteorologists use thermometers to find out how hot it is or if it's below freezing. Doctors use thermometers to check your body temperature — a very high or low body temperature means you're sick.

Example Sentences

See Examples For:

thermometer thermometers

If the thermometer fails to reach 20C anywhere in the UK, it will be the first time that has happened since 11 June.

From BBC ● Oct. 4, 2026

"Now we have empirical evidence using this geologic thermometer," Chiarenza said.

From Science Daily ● Sep. 20, 2026

More broadly, the thermometer climbed above 35 C in regions covering 80 percent of Europe’s residents, some 490 million people.

From Barron's ● Aug. 20, 2026

It’s a few minutes after 10 a.m. on a recent morning and the thermometer is closing in on 95 degrees, but Marc Papas isn’t fazed.

From Los Angeles Times ● Aug. 4, 2026

I notice the huge fund-raising thermometer behind Dr. Newman.

From "Merci Suárez Changes Gears" by Meg Medina

Even at sea, thermometers have registered record temperatures.

From Barron's ● Aug. 25, 2026

Today, gallium is widely used in semiconductors, telecommunications equipment, LEDs, laser diodes, solar panels, high performance computing, the aerospace and defense industries, and as a safer alternative to mercury in thermometers.

From Science Daily ● Jul. 9, 2026

Some new charcoal grills—traditionally the cook-anything-anywhere option—now require electricity to power internal fans and built-in thermometers.

From The Wall Street Journal ● Jun. 26, 2026

Late Friday, firefighters had been relying on drone-based thermometers to estimate the temperature inside the failing tank, which gave a reading of 61 degrees, with 50 degrees being the goal.

From Los Angeles Times ● May 23, 2026

It must have been about two o’clock when I saw Tino and Victor standing in front of one of those Pepsi thermometers.

From "Tangerine" by Edward Bloor

Related Words

• instrument
• thermostat