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

Inside, the temperature is 23C while outside the thermometer read 30C on Wednesday.

From Barron's ● Jun. 26, 2026

It is not impossible that parts of southern England and Wales could see the thermometer climbing even higher, into the mid-twenties Celsius.

From BBC ● May 13, 2026

Drizzle could dampen Southern California on Monday and Tuesday before a heat wave arrives just in time for Mother’s Day weekend — possibly pushing the thermometer to 90 degrees in downtown L.A. on Sunday.

From Los Angeles Times ● May 4, 2026

Basically, he wrote a hit piece on the thermometer instead of asking why he had a fever.

From Slate ● Apr. 17, 2026

I had brought a thermometer from the house to take his temperature, but I decided that could wait until morning.

From "Z for Zachariah" by Robert C. O’Brien

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

"Europe bakes in fierce heat" is the FT Weekend's headline as it reports the continent sweltered through a fifth day of record-breaking temperatures, with thermometers topping 40C.

From BBC ● Jun. 26, 2026

Two people in the area fainted as thermometers showed the temperature hitting 97 degrees.

From The Wall Street Journal ● Nov. 21, 2025

Newsom homed in on Trump’s climate change denials while speaking to New York Times reporter David Gelles at the paper’s Climate Forward forum on Wednesday, saying thermometers are not political.

From Los Angeles Times ● Sep. 24, 2025

Mrs. Tally had taken two jars and put thermometers in each, then covered one with aluminum foil and left the other open.

From "Two Degrees" by Alan Gratz

Related Words

• instrument
• thermostat