Ace - If something is ace it is brilliant. I used to hear it a lot in Liverpool. Kids thought all cool stuff was ace, or brill.
Aggro - Short for aggravation, it's the sort of thing you might expect at a football match. In other words - trouble! There is sometimes aggro in the cities after the pubs shut!
All right? - This is used a lot around London and the south to mean, "Hello, how are you"? You would say it to a complete stranger or someone you knew. The normal response would be for them to say "All right"? back to you. It is said as a question. Sometimes it might get expanded to "all right mate"? Mostly used by blue collar workers but also common among younger people.
Anti-clockwise - Counter-clockwise, in the U.S.!
Any road - Up north (where they talk funny!!) instead of saying anyway, they say "any road"! Weird huh?
Arse - This is a word that doesn't seem to exist in America. It basically means the same as ass, but is much ruder. It is used in phrases like "pain in the arse" (a nuisance) or I "can't be arsed" (I can't be bothered) or you might hear something was "a half arsed attempt" meaning that it was not done properly.
Arse about face - This means you are doing something back to front.
Arse over elbow - This is another way of saying head over heels but is a little more descriptive. Usually happens after 11pm on a Saturday night and too many lagers! Some Americans say ass over teakettle apparently!
Arse over tit - Another version of 'arse over elbow,' but a bit more graphic!
Arsehole - Asshole to you. Not a nice word in either language.
Arseholed - Drunk! Usually in the advanced stages of drunken stupor, someone would be considered "completely arseholed". Never me, of course! . . . .
As well - You chaps say also when we would say "too" or "as well". For instance if my friend ordered a Miller Lite, I would say "I'll have one as well". I often heard people saying something like "I'll have one also". Of course in Wales /England you wouldn't say it at all for fear of embarrassment! You'd order a pint of lager instead!
Ass - Your backside, but mostly a donkey!
Au fait - Another one of those French expressions that have slipped into the English language. This one means to be familiar with something. I'd say at the end of reading all this you'd be au fait with the differences between American and English!
I will, eventually complete the whole A – Z!