Blocks

Hi,

Forgive what may be a really basic question, but can anyone provide a dictionary definition of a "block" (in the Moodle sense)? I could not find it in the glossary or Moode Docs. I'm looking for a way to explain the term to non-technical people or those who are unfamiliar with Moodle.

Your suggestions would be very much appreciated! And forgive me if I have overlooked a really obvious place where this is given...