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

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Etymology

Origin of thermometer

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

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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

It was July in the Mojave Desert, and the thermometer climbed toward 110 degrees.

From The Wall Street Journal ● Oct. 10, 2026

"That's the basis of using the isotopes as a thermometer," Eagle 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

He had another pair which had a real thermometer in one and a real compass in the other.

From "Slaughterhouse-Five" by Kurt Vonnegut

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

One worker said: "We don't seem to have enough thermometers."

From BBC ● Jun. 16, 2026

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

From The Wall Street Journal ● Nov. 21, 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

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Related Words

• instrument
• thermostat

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