Yeah, Central Europe usually starts as far west as Germany, sometimes including Switzerland and Liechtenstein. Poland, Slovakia, and Hungary form the eastern edge, though those are often also just lumped into “Eastern Europe,” I assume because of their days as Warsaw Pact countries (when the diving line between Western and Eastern Europe was whether the country was behind the Iron Curtain or not). I’ve never heard France lumped into Central Europe.
I would not include France, as the seat of French government isn’t there. (This seems to be the norm: If you ask someone which in which continent France is located, they would say Europe.) I would just list the French Guiana, but include an asterisk about how it is a French territory.
Geologists distinguish continental plates from oceanic plates by the nature of the rocks that make it up. I don’t think anyone is going to advocate that the Pacific plate is a continent, although it does contain some land that’s normally considered part of a continent.
I answered “No”. The question as stated is “Which countries are in South America” and to me, that reads as “wholly in” or “mostly in”. France is no more in South America than the USA is in Polynesia or Türkiye is in Europe or Egypt is in Asia.
Basically, for me, “a small part is in” is not equivalent to “is in”. It’s purely a language issue for me, I don’t dispute that parts of French territory are in the South American continent.
I’d say the most common usage in everyday conversation is “the north”. E.g. “Are you heading to the north this weekend?” For more precision, “Northern Ireland” when talking about the political entity or the legal system and “the north of Ireland” when talking about the geographical area. Unless you’re a die-hard republican, in which case you may favour the term “the 6 counties”.
Looking in the other direction, the most common usage is “the Republic”. E.g. “They crossed the border into the Republic”. This is often abbreviated as “ROI” (e.g. “over 50% of our sales YTD have been in ROI”). Other usages are “the 26 counties” (this option is favoured by die-hard republicans) and (mainly in news reporting) “the State”, or just “Ireland” if you are not specifically distinguishing from the north (e.g. “Michael D Higgins is the President of Ireland”).
There is a Wikipedia page for this too, again with more than you probably want to know: Names of the Irish state - Wikipedia
Some years back, I went to Ireland as a tourist. I was talking about it to someone when I got back, and they said something about “Oh, you went to Great Britain”. “No, and an Irishman would consider that extremely offensive”. “I’m sorry, I meant the UK”. “That’s still just as wrong and offensive”, and I think they then managed to get it wrong a third time, in some way I can’t remember.
Oh, and just to add one more fine point to the Irish situation, “Ulster” is not synonymous with “Northern Ireland”. Ulster consists of eight counties, of which six compose Northern Ireland (i.e., a part of the UK), and two are part of the Republic.
Nitpick: Ulster has 9 counties, of which three are in the Republic.