Plain English Meaning
It is an agreed format for writing down navigation information so that every flight management system and GPS unit can read it the same way. Without a shared format, each manufacturer would store the data differently and the information could not be moved between systems reliably.
Full Definition
An international industry standard that defines how navigation data — such as airports, runways, navaids, waypoints, airways, and instrument procedures — is formatted and exchanged so it can be loaded into airborne navigation systems. It specifies a standardized record layout that database providers use when delivering navigation data to avionics manufacturers and operators.
Context Anchor
Seen in discussions of how published and information becomes the database information loaded into an navigation .