>>undershirt we call a vest (or singlet).
>
>Here it is a tank top or a "wife beater"

A tank top here is a sleeveless pullover, esp. the round-necked variety from the 70s

>
>>underpants
>

Yeah, briefs - but men's

>Underwear, briefs, gaunch
>
>>knickers
>
>This would refer to short pants that boys wore in the 1920's, sort of like Oliver Twist or a paperboy. Also refers to the same short pants worn by cross country skiers.

Knickers - Generally a girl's panties (uck - hate that word), but (more archaic) can be like soccer shorts.
>
>> meridian - central reserve
>
>Canada: median.

Aye, I think I got the US term wrong - should have been median :-)

>> meeeeeerrr - mirror
>
>In Canada: Canada In UK: Canader (lol)
>
>> US: ATM
>
>Bank machine

In UK only bank staff would call it ATM - Cashpoint, Cash machine, hole in the wall

Fanny Pack - Bum Bag ("fanny" has a WHOLE different meaning over here - let's just say that men don't have one)

cigarettes - (slang) fags! (yes, I know...)