Appears to launch small objects through the air.
Latin vado, "go", and possibly vasa, "implements, vessels"; but this part is obscure. (The letter "V" in Latin is also written "U", and pronounced as the English "W".) It could also come from Swedish vadd, which means "soft mass" (in this case it was gum), and French vas y, "go there", as Lupin did not just make the gum fly out of the key hole, but he directed it up Peeves's nose. The word could also just be based on the English wad, as in "a wad of gum".