Is “American” an ethnicity?

Only if you’re talking about Native American (American Indian).

Ultimately, yes. America has cultural traditions and it's one nation. It's not a tightly-bound ethnicity like the Danish or Koreans, but we have too much in common for our similarities to be reasonably denied.

If you really go into the idea, there are no ethnicities. What is Scottish? The Picts or some ancient stone-age people who lived there first? Or maybe the celts? or the Vikings that took it over, or the English who live just next door, or the French. We are all bastards if you go deep enough.

The bit that really tickles me is when people from the USA refer to black people in the UK as "British African-Americans". Um... yeah. No.

Technically yes, but they're descended from the native tribes. Hence called "negative Americans".

No it's a nationality unless you're native american

No. It’s a nationality.

murucan panda here!

Only if you're indigenous