3/
With the exception of the yard (foot, inch, &c.), which, at their current values, are likely 13th century inventions, all the other traditional units -- not just the names, but the actual values themselves -- are much older than that and are not "Imperial" at all. So hate on the U.S. Customary System all you want (I'm not defending it and don't want to discuss that here), but please don't call it "Imperial." That's just wrong.