Plain English Meaning
A short connecting route on an approach chart that takes you from where you are in the enroute system to the starting point of the actual instrument approach.
Full Definition
A route depicted on instrument approach procedure charts that provides a path from an enroute fix or navigation aid to the initial approach fix (IAF) of an instrument approach procedure.
Context Anchor
Seen on instrument approach charts, especially when moving from the en route portion of an IFR flight into the approach procedure.