crawl space

noun2

1. •
   A level, narrow opening underneath the bottom of a building or storey used to give access to pipes, cables and other utilities.

   • When he couldn’t take another step he hid under a lonesome gray house and squatted in the fetid water of the crawl space. — 2019
2. •
   A severely height-limited basement or semi-basement of a building, of less than half a storey high.