Merriam-Webster Logo
SINCE 1828
Menu
×

An Encyclopædia Britannica Company

vacuum tube

noun

Definition of vacuum tube

  1. :  an electron tube evacuated to a high degree of vacuum

See vacuum tube defined for English-language learners

See vacuum tube defined for kids

Explore M-W

emoji-the-quiz
The Emoji Quiz
image386126722
Words That Come From the Dinner Table
alt-597233d35a146
Trending: 'Scaramouch,' Scaramucci Possibly to Fandango
alt-59721dd897313
The 'Best' Way to Sign Off On An E-mail

First Known Use of vacuum tube

1859

VACUUM TUBE Defined for English Language Learners

vacuum tube

noun

Definition of vacuum tube for English Language Learners

  • : a glass tube that was used in the past in computers, televisions, etc., to control the flow of electricity

Medical Dictionary

vacuum tube

noun

Medical Definition of vacuum tube

  1. :  an electronic device in which conduction by electrons takes place through a vacuum within a sealed glass or metal container and which has various uses based on the controlled flow of electrons

Learn More about vacuum tube

  1. Britannica.com: Encyclopedia article about vacuum tube

Seen and Heard

What made you want to look up vacuum tube? Please tell us where you read or heard it (including the quote, if possible).

show hide

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

WORD OF THE DAY

advise

play

to counsel, recommend, or inform

Get Word of the Day daily email!

TRENDING NOW

  1. scaramouch A new White House communications director

  2. non sequitur “It does not follow”

  3. admiral's mast A massive search ends with an 'admiral's mast'.

  4. calumny 'An untrue statement that is made to damage someone's reputation'

  5. kakistocracy Frustrated Twitter users have been searching for this word.

SEE ALL

BROWSE DICTIONARY

vacuum tube

Test Your Vocabulary

The Emoji Quiz

  • emoji-the-quiz
  • What phase of the moon is this: 🌖 ?
True or False

Test your knowledge - and maybe learn something along the way.

TAKE THE QUIZ
SCRABBLE® Sprint

Test Your Knowledge - and learn some interesting things along the way.

TAKE THE QUIZ

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

Words at Play

alt-59721dd897313
The 'Best' Way to Sign Off On An E-mail

Give them your best

image386126722
Words and Phrases That Come from the Dinner Table

Fill your plate with these surprising food words

ghost-being-disinvited-from-party
'Disinvite' or 'Uninvite'?

A disinvited guest is an uninvited problem

alt-596f730ceb5ae
Words We're Watching: 'Scoby'

Kombucha lovers unite.

Ask the Editors

video-title-words-of-the-year-1066
Words of the Year: 1066

Or, Why Pig Meat is Called 'Pork' and Cow Meat is Called 'Beef'

payday
How Often Is 'Biweekly'?

Don't get us started on 'bimonthly'

video-irregardless-grammar-peeve-blend-of-the-synonyms-irrespective-and-regardless
Irregardless

It is in fact a real word (but that doesn't mean you should use it).

video-moose-goose-weird-plurals
Weird Plurals

One goose, two geese. One moose, two... moose. What's up with that?

Word Games

emoji-the-quiz
The Emoji Quiz

Think you’re an emoji 👓 expert? Let’s see 🤔

Take the quiz
image941935269
A Game of Thrones Word Quiz

In the Game of Thrones quiz, you learn some new vocabulary. (It’s quite safe, really. You will not die.)

Take the quiz
True or False
True or False?

Test your knowledge - and maybe learn something along the way.

Take the quiz
SCRABBLE® Sprint
SCRABBLE® Sprint

SCRABBLE® fans, sharpen your skills!

Play the game