Look up A4 in Wiktionary, the free dictionary.

A4 or A-4 may mean:

• The standard paper size: A4 paper size
• The A4 road in England that runs from London to Bristol
• The A4 motorway in Switzerland that runs from Schaffhausen to central Switzerland
• The A4 highway in France that runs from Paris to Strasbourg. It is a part of the European routes E50 and E25 .
• The LNER's A4 class of steam locomotives, including Mallard, which holds the world speed record.
• A4, the actual model number for the German V-2 rocket.
• Audi A4, a luxury car made by Audi.
• A-4 Skyhawk, the military attack aircraft.
• the IATA code for Southern Winds