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

2

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

interstitially

ˌin-tər-ˈsti-shə-lē 

adverb

Examples of interstitial in a Sentence

Recent Examples on the Web

She was voted the vice president of the academy class and consistently scored high on all of the interstitial tests. — Wilbert L. Cooper, Longreads, 25 Aug. 2026

Each interstitial piece became flash fiction, where each of the characters took over the narration of their own stories. — Literary Hub, 21 Aug. 2026

And for the many interstitial scenes in the woods, Franklin Canyon and its lush forest stood in. — Amanda Karkoutly, Los Angeles Times, 18 Aug. 2026

Some studies have described BPC-157 being used to treat knee pain, a chronic bladder condition known as interstitial cystitis and ulcerative colitis, a common type of inflammatory bowel disease that can cause inflammation and ulcers in the colon. — Jacqueline Howard, CNN Money, 31 July 2026

Word History

First Known Use

1646, in the meaning defined at sense 1

Rhymes for interstitial

• artificial
• beneficial
• cicatricial
• nonjudicial
• nonofficial
• prejudicial
• sacrificial
• superficial
• unofficial
• extrajudicial
• semiofficial
• initial

Kids Definition

interstitial

adjective

in·​ter·​sti·​tial ˌint-ər-ˈstish-əl 

: relating to or located in the interstices

interstitially

-ˈstish-ə-lē 

adverb

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

interstitially

-ə-lē 

adverb