A “belgicisme” is any word or phrase that’s unique to Belgian French (aka not France French), so here are some of the words and phrases that set the French apart from the Belgians.
You could ask for just a latte at a restaurant, but if you want to pass as a Belgian, ask for a “lait russe” or a “Russian milk.”
“Savoir” instead of “pouvoir”
“Pouvoir” is the verb for “to be able,” and it’s what you would usually use if you were asking someone to do something for you. (à la “Can you pass me a plate?”) However, here in Belgium, you would use the verb “savoir” which is “to know.” So much to the ire of my French housemates, you would ask someone “Do you know how to pass me a plate?” (“Of course I know how to pass a plate!”)
In France, you would call your cell phone a “portable,” but in Belgium, a cell phone is a “GSM,” which is short for “Global System for Mobil Communications.”
“S’il vous plait” instead of “Voilà”
In France, when someone hands you something (change, a receipt, etc.), they’ll say “voilà.” In Brussels, you’ll hear “s’il vous plait,” which as you may know, translates to “please.”
French has a notoriously frustrating counting system: 70 becomes “sixty-ten,” 71 is “sixty-eleven,” but then 80 is “four-twenty” and 90 is “four-twenty-ten.” Belgian French has thankfully decided that 70 and 90 should have their own words “septante” and “nonante,” but unfortunately still uses “four-twenty” for 80. Sigh.
I live with five Frenchmen/women, so if I’m being completely honest, I spend a lot of my time speaking/hearing/absorbing France French, but it’s still nice to have these Belgicismes in my pocket for a) when I’m out and about in Brussels or b) when I feel like irking my housemates ;)