Nationality

When we say that someone is from America, we say they are American. Many other countries can be altered to have -an at the end in the same way.

When we say that someone is from Japan, we say they are Japanese. Many other countries can be altered to have -ese at the end in the same way.

When we say that someone is from Spain, we say they are Spanish. Many other countries can be altered to have -ish at the end in the same way.

Of course, there are minor adjustments that have to be made for all of the above examples to work, but they're common enough that we are familiar with them. France seems to be mostly unique in that the entire country's name is changed when referring to the nationality instead (from "France" to "French"). I can't think of many similar examples other than Welsh (for Wales) and Dutch (for the Netherlands).

Wouldn't it be funny, though, if the -ch used for France worked with other countries? Well, perhaps not in all cases, but it sure would for people from Belgium! We could call them the Belch!