interstitial
adjective
in·ter·sti·tial
ˌin-tər-ˈsti-shəl 
1
: occurring in or being an interval or intervening space or segment : of, relating to, or forming an interstice
an interstitial space
… the site has been running interstitial ads, which consist of a full page of advertising between editorial pages, for a little more than a year.—
Carl Sullivan
Carl Sullivan2
a
: situated within but not restricted to or characteristic of a particular organ or tissue
—used especially of fibrous tissue
b
: affecting the interstitial tissues of an organ or part
interstitial cystitis
3
: being or relating to a crystalline compound in which usually small atoms or ions of a nonmetal occupy holes between the larger metal atoms or ions in the crystal lattice
Examples of interstitial in a Sentence
Recent Examples on the Web
Imagine not suffering existential dread over Tilly Norwood; imagine the freedom to choose to use AI for interstitial shots without kicking the Letterboxd hornets’ nest, as did the brothers Cairnes with Late Night With the Devil back in 2024.
—Andy Crump, Time, 31 Oct. 2025
During a stage of sleep called slow-wave, neurons pulse rhythmically, pumping cerebrospinal fluid through their interstitial gaps to wash themselves clean.
—Rowan Jacobsen, Harpers Magazine, 24 Oct. 2025
At present, an interstitial pop-up advertises Reishi as 25 percent off; purchasing six sheets or more unlocks 50 percent off.
—Alexandra Harrell, Sourcing Journal, 17 Oct. 2025
Its general sensibility seems more Superstore than The Office, down to the interstitial montages of customers acting up in the perpetually overcrowded waiting room.
—Angie Han, HollywoodReporter, 13 Oct. 2025
See All Example Sentences for interstitial
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Andy Crump, Time, 31 Oct. 2025
During a stage of sleep called slow-wave, neurons pulse rhythmically, pumping cerebrospinal fluid through their interstitial gaps to wash themselves clean.
—Rowan Jacobsen, Harpers Magazine, 24 Oct. 2025
At present, an interstitial pop-up advertises Reishi as 25 percent off; purchasing six sheets or more unlocks 50 percent off.
—Alexandra Harrell, Sourcing Journal, 17 Oct. 2025
Its general sensibility seems more Superstore than The Office, down to the interstitial montages of customers acting up in the perpetually overcrowded waiting room.
—Angie Han, HollywoodReporter, 13 Oct. 2025
See All Example Sentences for interstitial
Cite this Entry
“Interstitial.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/interstitial. Accessed 11 Nov. 2025.
Copy CitationKids Definition
interstitial
adjective
in·ter·sti·tial
ˌint-ər-ˈstish-əl
: relating to or located in the interstices
Medical Definition
interstitial
adjective
in·ter·sti·tial
ˌint-ər-ˈstish-əl
1
: situated within but not restricted to or characteristic of a particular organ or tissue
—used especially of fibrous tissue
2
: affecting the interstitial tissues of an organ or part
interstitial hepatitis
3
: occurring in the part of a fallopian tube in the wall of the uterus
interstitial pregnancy
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