Like many other fields, science has its own style of communication full of specific jargon and guided by unwritten rules.  Most of the posts on this blog focus on breaching this barrier to the public’s understanding and appreciation of science.  In this series, I’d like to take another approach by highlighting scientific words which have escaped the confines of jargon to reach a broader appeal because of their sound or their evocative power as metaphors.  Today’s word is interstitial. [Previous words of science were petrichor, alluvium, nychthemeron, and crepuscular.]

Despite its fancy sound, interstitial (pronounced to rhyme with ‘artificial’) has a very simple, straightforward meaning.  It just means “in the gaps in between things”.  It comes from the Latin word, interstitium, which derives in turn from inter=”between” and sistere=”to stand”.  Interstitial literally translates as “standing between”.  If you want a great noun for a (usually narrow) gap between two things, you can use ‘interstice’ — or, just for fun, why not ‘interstitial space’?  That’s the joy of scientific writing; instead of a simple, friendly word like “gap”, we can use intimidating phrases like “interstitial space”!  (I just discovered that “interstitial space” actually has a specific meaning in architecture — it’s the extra space left between floors in a building for all the pipes and wiring.  Neat!  Wikipedia even has a page listing things that are interstitial.)

Interstitial is a bit different from the other words in this series so far. I don’t think it’s really escaped out into the larger world — I’ve mainly seen it used in scientific or technical contexts.  It does seem to be getting a bit more usage beyond science these days, but mainly because of “interstitial ads” — the ads that show up in the middle of an article, in between two paragraphs.

Here are a few examples I found.  The first quote is the earliest citation I found in the OED and is fun to read aloud; the second is from Robert Hooke’s Micrographia, which is where he coined the biological term ‘cell’!

In oyled paper..the interstital divisions being continuated by the accession of oyle, it becommeth more transparent.

Sir T. Browne
Pseudodoxia Epidemica, 1646

And, according as these pores are more or greater in respect of the interstitial bodies, the more transparent are the so constituted concretes; and the smaller those pores are, the weaker is the Impulse of light communicated through them, though the more quick be the progress.

R. Hooke
Micrographia, 1665

‘The Brook’, with its charming interstitial soliloquy..will..always rank among Mr. Tennyson’s happy efforts.

W.E. Gladstone
Gleanings, 1859

The reason I like interstitial is that it somehow just sounds right.  It might be the repetition of ‘t’ that makes it feel like a word that must have something to do with being squeezed between things.  I sometimes get that sort of feeling about a word; it’s as though no other combination of sounds could capture the meaning quite as well.  The French word coincé (pronounced kwan-say with the ‘an’ from answer), which means ‘stuck’, is the same.  It’s hard for me to imagine a better word for ‘stuck’, though I have no idea why.  What about you?  Are there any words that have always sounded ‘just right’  to you, as though they couldn’t possibly have any other meaning?