ARP

• aerodrome reference point

  ICAO

• air-report

  General

• airport reference point

  General

• airport reservation position

  General

ARP has 4 meanings; the right one depends on context. A weather report, a NOTAM or an ATC clearance. Got a NOTAM full of contractions? Paste it into the decoder.

Source: FAA Order JO 7340.2 Contractions. Not for operational use.