vacuum tube

American  

noun

1. especially British, vacuum valve.  an electron tube from which almost all air or gas has been evacuated: formerly used extensively in radio and electronics.

2. a sealed glass tube with electrodes and a partial vacuum or a highly rarefied gas, used to observe the effects of a discharge of electricity passed through it.

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vacuum tube British  

noun

1. another name for valve

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vacuum tube Scientific  

1. An electron tube from which all air has been removed. The vacuum ensures transparency inside the tube for electric fields and moving electrons. Most electron tubes are vacuum tubes; cathode-ray tubes, which include television picture tubes and other video display tubes, are the most widely used vacuum tubes. In other electronic applications, vacuum tubes have largely been replaced by transistors.

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Etymology

Origin of vacuum tube

First recorded in 1775–85

Example Sentences

For a time, it used 5 million volts of electricity to shoot hydrogen nuclei down a vacuum tube at up to 100 million miles an hour.

From The Wall Street Journal • Oct. 7, 2025

In the last century, our capacity to store and process data has soared, with electronics marching from the vacuum tube to the transistor to today’s semiconductor chips.

From Scientific American • Jun. 14, 2023

It accelerates electrons within a long vacuum tube to high energy and near–light-speed, while magnets steer them around the ring.

From Science Magazine • May 3, 2023

At the bank drive-through, they watched endorsed checks whoosh through the vacuum tube toward the teller waiting at the window.

From Washington Post • Feb. 6, 2023

There were no windows, for there was no scenery to see in the subsurface vacuum tube.

From "Scythe" by Neal Shusterman