JohninKansas says that

Although I've used the term "wallet" in deference to prior use in the thread, if it folds up to fit in a rear pocket in US usage it would be called a "billfold."

Maybe that's the usage in Kansas, John, but in Minnesota, where I grew up, and in Indiana, where I've lived for the last 43 years, the folded thing in my back pocket has been a wallet. I recognize the word "billfold", but I'm not sure I ever use it.

And as to the word "trousers", I recognize that too, but in 74 years I don't think I've ever referred to the rags that kiver the nekkidness of me nether parts as "trousers". They are "pants", or occasionally "slacks". And frankly, I've never liked the word "slacks" for men; "slacks" are what women wear.

Dave Oesterreich