For the Americans: a UK "jumper" is not a kind of apron or dress but a kind of pullover or sweater.
I agree: it should be made clear that jumper here does not mean someone who jumps, but what Americans call a "pullover" or "sweater". (I am American, and i was confused briefly.)
As an American I was completely unaware that "jumper" could mean a "sweater." I had to look it up in the dictionary. Although I am happy to now know a "new" word, may I suggest "siwmper" be identified as "jumper/sweater" or "jumper or sweater"?
Does 'Si' Not Make A 'Sh' Sound Before A 'W'?
"Si" does make a "sh" sound and "siwmper" is the phonetic Welsh spelling of the British English word "jumper". As Welsh doesn't have the "j" sound, it comes out as "shumper".