[Charles Martel]

It originally meant any small grain seed. The salt used in curing meat was not fine ground like you would get at the table but it was not in large chunks either. It was corned which means it was broken down in to roughly uniform pieces the size of a small grain seed.

This was the size of the salt used for preserving meats so corned (salted) beef as opposed to fresh or smoked.

This is a point of divergence between the U.K. and North America - the Brits call this "salt beef", and another canned/tinned meat product is known there as "corned beef". The latter is just cooked finely-ground (corned) beef, no salt-curing used. It's like a beef version of Spam, packed in gelatin. WWI combat rations, IIRC, also referred to as "Bully Beef".

I'm not sure how the naming drifted, but it may have to do with the fact that salt-cured beef is sold in similar cans.

[Harmless Teddy Bear]

Two countries separated by a common language.

There is a Brit that is currently living in the US and he goes into why it is called "this" in the UK and "that" in the US.

It can be quite interesting to see how many words used in American do not come from English at all.