Wikipedia states that the Ø symbol can be used to denote diameter, but I've certainly never encountered it being used in this way in Britain.

I don't recall ever seeing this in American documents. I have recently come across the symbol in German documents, and I translated it as "Average."

The symbol Ø is indeed used in engineering drawings (blueprints) to denote diameter, but not any sort of average.

I believe the German word for diameter is Durchmesser (not Durchscnitt)

da diese seite in englisch ist, nehem ich an ja
http://www.symbols.com/encyclopedia/47/474.html

#4: that link is full of errors. It says, for example, that Ø is the Greek letter phi. That is incorrect; the Greek letter is Φ or φ. I would not trust anything in that Web site.

The International Standards Organization (http://www.iso.org/iso/about/discover-iso_iso...) has developed symbols for use on mechanical and engineering drawings and they are recognized and used around the world. The symbol for diameter is Ø.

Durchmesser = diameter
Durchschnitt = average or section

Support Bob C. - the symbol Ø is officially reserved for denoting the diameter.
However, you will find this symbol in many texts used as "average", at least in the German-speaking area. They are just too lazy for writing "durchschnittlich" or "im Durchschnitt", because the symbol gives you the idea. And obviously, many people recognize it that way...

Just to add that I also only know the symbol as meaning diameter (I am a Brit).

It must be similar to the misuse of the @ symbol here in LEO to signify "to."

I have never encountered Ø meaning "average." Perhaps it is used that way in Europe (as the bicyclist says).

Warning: TOTALLY OT
Dunno, I think the @ thing is pretty standard these days, you'll see it pretty much everywhere online. Don't think it can really qualify as misuse, as it's an internet thing that must be derived from e-mail (which uses the sign in addresses), and it would be hard to argue that the use of "@" in that an e-mail address is "wrong".

BTW, I always read it as "at", not "too" (i.e. the following is directed "at" XYZ)...

x, you're right, of course; through much Internet and texting use, it has become established, even though it has evolved quite far away from its original use and meaning. But no harm in that.

Früher war das Wort für den Kreisdurchmesser auch "Durchschnitt", daher hat sich das Symbol auch für den statistischen Durchschnitt durchgesetzt.

Eine solche Homologie existiert im Englischen nicht, daher fände ich dieses Symbol dort unpassend.

Du meinst sicher "Homonymie". :-)