interstitial

American  

[in-ter-stish-uhl] / ˌɪn tərˈstɪʃ əl /

adjective

1. pertaining to, situated in, or forming interstices.

2. Anatomy. situated between the cells of a structure or part.

   interstitial tissue.

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noun

1. Crystallography. an imperfection in a crystal caused by the presence of an extra atom in an otherwise complete lattice.

interstitial British  

/ ˌɪntəˈstɪʃəl /

adjective

1. of or relating to an interstice or interstices

2. physics forming or occurring in an interstice

   an interstitial atom

3. chem containing interstitial atoms or ions

   an interstitial compound

4. anatomy zoology occurring in the spaces between organs, tissues, etc

   interstitial cells

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noun

1. chem an atom or ion situated in the interstices of a crystal lattice

Other Word Forms

• interstitially adverb

Etymology

Origin of interstitial

1640–50; < Latin interstiti ( um ) interstice + -al ¹

Explanation

Interstitial has to do with small spaces, called "interstices." Interstices can be literal spaces, like the gaps between your teeth, or they can be figurative, like the few minutes you have between classes. You'll notice that when the noun interstice becomes the adjective interstitial, the -ce- changes to a -ti-. That's a fairly common spelling shift — difference becomes differential, for instance, where the -ti- is actually pronounced like -sh- or -ch-.

Example Sentences

Those conditions are pulmonary arterial hypertension and pulmonary hypertension with interstitial lung disease.

From Barron's • Mar. 30, 2026

Salmon is married to artist and illustrator Fiona Hawthorne, who previously revealed she was diagnosed with a rare lung condition, interstitial lung disease, which requires her to use an oxygen tank.

From BBC • Jan. 1, 2026

And there’s a lot of the interstitial stuff that I took from her biography, fusing with my biography, because even if you sing a song everybody knows, you’re doing it with your lungs.

From Los Angeles Times • Dec. 19, 2025

From a certain point of view, it makes sense to concentrate the art into discrete thematic galleries, and to treat the space between them as flowing interstitial fluid through which the visitor can meander happily.

From The Wall Street Journal • Oct. 29, 2025

They are part of each other, interstitial: lodged between each others cells.

From "Vincent and Theo: The Van Gogh Brothers" by Deborah Heiligman