Please, no answers like "freedom units". That's what comments or chat is for.

My old physics prof always called it the "Miserable English System". But mostly either "English" or "imperial", when context or the units named are not sufficient to make it obvious.

We don't refer to it by any name, usually. There isn't much call for a name for the collection of units, any more than there's a call for the a name for the specific set of denominations of US currency of a penny, a nickel, a dime, a quarter, $1, $5, $10, $20, $50, and $100 bills. That's just the way it is, even in theory if there are other options. Having said that, when speaking of the American system of units specifically in the context of contrasting it with the metric system, I've sometimes heard it called the Imperial system, though that's technically inaccurate.

Do Australians really speak about their "imperial" system everyday? Isn't it just their measurements system? What's the point of being specific so often?

@Josh See my answer. You've got the right of it.

'I've sometimes heard it called the Imperial system, though that's technically inaccurate.' But English is still referred to as English, even if other nations have borrowed it.

Just wondering - is the term US Size widespread?

@EdwinAshworth It's not inaccurate because "America is no longer in the Empire", it's inaccurate because the American system is actually different (deviates, if you prefer ;) from the Imperial system. For example, a US gallon of milk would only fill 83% of an Imperial gallon container.

@Lawrence I'm not at all handy. I don't use tools much. I think you'd Oldbag (who answered below about buying tools), or StoneyB, who if memory serves, was a carpenter for a while.

@DanBron Thanks. My question was motivated by Oldbag's post and your comment to it, followed by some web surfing. I recalled that some hardware (nuts and bolts, as it turned out, though I checked screwdrivers first) come in two slightly different size ranges that are so close that one can start putting them together, but sufficiently different to cause frustration when they get stuck part way through. I'll just wait for some knowledgeable person to come by and comment. :)

I'm BrE, not American. I sometimes use sterling to distinguish our currency from the Euro, but to be honest if I'm in, say, Belgium, I usually just say I want to pay in English (all Europeans would understand that, but I wouldn't expect many of them to know sterling). For measurements it's usually imperial (especially for lengths of screws, pipes, etc.), but once in a blue moon I might use avoirdupois for the (pounds & ounces) weights system.

@DanBron There are differences between the American system of communicating and English, too, but that doesn't stop the term 'English' being used over there.

@EdwinAshworth "English" has an established meaning which covers the British and American varieties. "Imperial" has an established meaning which covers only the British units, and specifically not the American units. It doesn't have to be this way, of course, but it is, and there's no arguing with it. And anyway, there's good reason for it. Non-ambiguity is critical in technical communications about quantities, weights, lengths, etc, because if there's any ambiguity, things can go wrong, from inconvenient to catastrophic.

@Lawrence: Re nuts and bolts, another complication is that both inch (referred to as SAE) and metric come in (at least!) two different thread pitches, coarse and fine. So you can have same-size nuts & bolts that don't screw together. Then if you happen to be into older British sports cars, there are Whitworth sizes, which are different from both metric and SAE.

@FumbleFingers If I wanted to refer to British money as distinct from the Euro, I'd say "pounds" before any alternative. Talking about "English money" suggests that you don't know the name of it and/or don't know that the Northern Irish, Scots and Welsh also use it.

@David: There aren't many things I might buy in Belgium that cost less than a pound, but even if it's a cup of coffee costing £1.50 I'd still think it a bit odd to say Can I pay for that in pounds? as I proffer one pound coin and one 50p piece. But whereas I might say I want to pay in English to a Belgian at the till, I'd usually say Don't worry if you've got no euros left - you can pay in sterling here to my Anglophone fellow traveller.

@EdwinAshworth: There are also differences between the British system of communicating and English. English is much bigger than BrE, which is one (small but important) dialect.

@EdwinAshworth: Other nations have not "borrowed" English, any more than has the nation of the United Kingdom borrowed it. No English-speaking nation has borrowed English. Modern BrE English is as different from 16th-century London English as is modern AmE or AustralianE or IndianE or... BrE has just evolved differently - it is not something that has remained constant and was borrowed by others.

@Josh Australians usually use metric, but sometimes use imperial (people's height, cooking), so we need the ability to contrast the two systems.

In a situation requiring distinction, like specifying nuts and bolts, terms like SAE and Metric are used, as jamesqf mentioned. In typical usage, though, Americans don't use a special term to refer to our system of units. We only add a term to distinguish "non-standard" systems, like metric.

I don't believe most Americans know that their system is different than the "English English System" (I'd guess that might be true in reverse as well?) It's really the English who complicated things, altering their system in 1824 without consultation! That said, it's indeed a right mess. Sort of like how the US latched onto the early metric system, took on the bar (and mb) for many pressures... and then metric changed to the Pascal. At least 1 mb = 1 hPa. I'd say most Americans feel shortchanged that you keep changing on us (except that honestly most Americans have no idea!)