dead space

noun

: the portion of the respiratory system which is external to the bronchioles and through which air must pass to reach the bronchioles and alveoli

Word History

First Known Use

circa 1923, in the meaning defined above

Time Traveler
The first known use of dead space was circa 1923

Rhymes for dead space

See All Rhymes for dead space

Browse Nearby Words

dead soldier
dead space
dead spot
See all Nearby Words

Cite this Entry

“Dead space.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/dead%20space. Accessed 20 Apr. 2025.

Copy Citation

Share

Medical Definition

dead space

noun
1
: space in the respiratory system in which air does not undergo significant gaseous exchange see anatomical dead space, physiological dead space
2
: a space (as that in the chest following excision of a lung) left in the body as the result of a surgical procedure
Love words? Need even more definitions?

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

Popular in Grammar & Usage

See More

The Difference Between 'i.e.' and 'e.g.'

'Affect' vs. 'Effect'

Words You Always Have to Look Up

Democracy or Republic: What's the difference?

Every Letter Is Silent, Sometimes: A-Z List of Examples
See More

Popular in Wordplay

See More

What do SCOTUS, POTUS, and FLOTUS mean?

8 Words with Fascinating Histories

8 Words for Lesser-Known Musical Instruments

Birds Say the Darndest Things

10 Words from Taylor Swift Songs (Merriam's Version)
See More

Popular

See More

The Difference Between 'i.e.' and 'e.g.'

What do SCOTUS, POTUS, and FLOTUS mean?

8 Words with Fascinating Histories
See More

Games & Quizzes

See All
Play Quordle: Guess all four words in a limited number of tries. Each of your guesses must be a real 5-letter word.
Quordle Can you solve 4 words at once?
Play Blossom: Solve today's spelling word game by finding as many words as you can using just 7 letters. Longer words score more points.
Blossom Word Game Pick the best words!
Play Missing Letter: a crossword with a twist. Each of the 25 puzzle words start with a different letter of the alphabet. Which letter is missing?
Missing Letter A daily crossword with a twist
name that thing flower edition
Name That Flower Can you tell the difference between a lilac and a...
See All