Plain English Meaning
The big, complete navigation data files that data suppliers keep up to date. The smaller files loaded into your aircraft's GPS or flight management system are pulled from these.
Full Definition
The official, source navigation databases maintained by aviation data suppliers (such as Jeppesen or Lido) that contain the full, current set of navigation information — airports, runways, navaids, airways, fixes, instrument procedures, and airspace — from which the smaller, aircraft-specific navigation databases loaded into avionics units are derived.
Context Anchor
Seen in discussions of instrument , updates, and storage limits in panel-mounted or portable .