Plain English Meaning
It is the spot in the avionics database where the name or code of an instrument approach is stored, so the system knows which approach you are asking for when you pick one from the menu.
Full Definition
A data field within an avionics database record that holds the unique identifier assigned to a specific instrument approach procedure, allowing the navigation system to recognize, load, and display that approach when the pilot selects it.
Context Anchor
Seen when selecting, loading, or checking an instrument approach in installed avionics or a navigation database.