The human brain increases its total volume by folding its surface area into peaks and troughs called gyres and sulci. The process whereby this happens is called gyrification (not sulcification, for some reason). The total surface area of the brain is about one or two pages of newspaper, much larger than the surface area of the skull.

The intestines curve back and forth within the abdomen and increase their total length to about 22 feet. This is not exactly inward folding, but the inside of the intestine has villi and microvilli that do look like an inward folding, increasing the surface area by several orders of magnitude, until it is about the total area of a tennis court!

I am looking for a word generally appropriate to this geometry, but applicable in a non-biological context. It should carry connotations of increasing complexity induced by inward folding. Gyrified is bad because nobody knows what it means, it only talks about brains, and could have been sulcified. I have been using involuted, but it’s not quite right because it involves rolling or curling in a spiral manner, coming from the architectural term volute, which is a spiral ornament on an Ionic column.

  • 1
    I think you want, somewhat ironically, convoluted. :)
    – Dan Bron
    Commented Jul 26, 2020 at 13:18
  • @DanBron I thought that "to convolute" and "convolution" would be suitable answers to the question but the online dictionaries do not support me. For instance Lexico defines convolute as a transitive verb but restricts its use to literature and language by saying "Make (an argument, story, etc.) complex and difficult to follow." There are other definitions of both words but "convolute" is only listed as an adjective with a specifically biological meaning and "convolution" is only listed as a noun describing the result of the folding. Very odd.
    – BoldBen
    Commented Jul 26, 2020 at 14:06

1 Answer 1


Another biological term is invagination which means involution to form a cavity.

Some other non-biological words might be wrinkled or spiraled which generally imply greater surface-to-volume ratios. An uneven surface may be corrugated or may have furrows in it.

  • I'm reminded of the word tesseract. Commented Jul 26, 2020 at 16:13

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.