Dress code says "professional wear"

Hello,

I've been invited to a function at work and for dress code it says "professional wear".

Is this the same as formal? In other words... what do I wear?!

Trouser/skirt suit with a collared shirt.

I expect it's just what you'd wear to work.

Unless it's jeans and casual dress of course.

And unless your a postman..

or a hooker

must be American,
only my American colleagues are always asking that.

Wear shoes.

We had a corporate circular, years ago, that explained, among other the things that the following wear not acceptable casual business wear, the memo was sent world wide (70K serfs) when only the Americans had Friday CBW; Europe is still laughing.

Do not wear:

1) Tube tops
2) Sleaveless T shirts or Ripped jean
3) Flip flops
4) Short shorts
5) Baggie pants showing undies

For God's sake, I'm a respectable primary teacher and I'm not American.Thanks guys for the serious replies and for making me laugh !!

Skirt or trousers, collared shirt or blouse.
<rest of post edited.>

Dungareens

Seriously?

What is Friday CBW?