Learn English – the device called when you use the same word but with two different meanings in a phrase for effect

Am I right in saying that in the US the primary usage of the word is for a man to call a woman a cunt as an accusation of reprehensible moral standards, as well as it being laced with undertones of misogyny and sexism? In this context, extreme offensiveness is very much the intent.

In the UK it’s not really used that way; rather it’s just another generic insult that, while still regarded as the strongest of our swear words, is losing its impact over time. As well as occasionally being thrown at each other by antagonists in an argument, it’s quite widely used between friends (men, predominantly) – either towards each other in a playful sense, or to refer to other people of whom the speaker disapproves.

So I’d suggest that different reception of the word in the two countries is down to these different predominant uses.

Flat is used in British English, and apartment is used in North American English. The exact meaning of the word apartment depends on where you live.

In large parts of Canada and in or near New York City, it is used for a residence in a multi-unit building; this meaning is the one given by OALD, and is a synonym of the British word flat.

In most of the rest of the U.S. and on the West Coast of Canada, the word apartment is reserved for a rented residence in a multi-unit building; if the residences in the building are individually owned, they are called condos.

As Ben Hocking says in his comment, an apartment doesn't have to be on just one story (although the majority of them are). But if you live in a multistory residence which doesn't have anything either above or below your unit, even though there are residences attached on both sides, this is more commonly called a townhouse. If there are just two residences in the same building, you have a duplex.

See also this question.