>undershirt we call a vest (or singlet).

Here it is a tank top or a "wife beater"

>underpants

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.

>on-ramp/off-ramp - sliproad/exit sliproad

In Canada you would likey hear "exit".

> meridian - central reserve

Canada: median.

>stick-shift - gear stick;

Canada: gear shift

> meeeeeerrr - mirror

In Canada: Canada In UK: Canader (lol)

> US: ATM

Bank machine