How common is the “deci” prefix in the metric system?

Nah, that is too easy! And it is absurd when US-Americans use a different spelling than the rest of the world for a system that they themselves do not use. Sorry, completely unacceptable.

There is no doubt. As @hogarth just pointed out, deka- is valid in at least one major form of written English, and I don’t know about Slovakia, but in Norway it is the only valid spelling.

It’s not “the rest of the world” just because it is in English. Go to the Wikpedia page for deca- and look at the links going to other language versions. There’s a lot of "deka-"s in those that use latin characters.

OK, I surrender and unilaterally drop the highjack. Still weird, the International System should be the same in all language versions, that is why it was created. At least the abbreviations seem to be identical, that is something.

It was created so there wouldn’t be confusion, so as long as it’s standardized in each language and no one decides that in their language deci- should mean 1/100ths, there is no issue. Since not all languages use the same alphabet the French version can’t apply universally anyway, but I find nothing in the standard mentioning this, even though the , vs . as decimal separator is mentioned several times.

The main Norwegian dictionary entry for the SI specifies that spellings are adapted to local languages, but I’ve given up finding out where that is actually written down as an official decision.

That is good to know, another detail so many countries get wrong. I’m starting to think this highjack deserves a Pit entry on its own.

Oh, you won’t enjoy this then. SI is fine with either.

I wonder what I have done to them. I’m not enjoying nothing much today, I must admit. I always get bad tempered when my feet hurt, maybe it’s that.

Milli- is another one that commonly changes by language. Is it one L or two? In many languages, it’s just one. In English, French, German, Hungarian, Italian, it’s two. In Spanish, Polish (and I’m guessing the rest of the Slavic languages that use Latin script) Romanian, Lithuanian, etc, it’s one.

And then there’s the unit itself, like meter. All over the place.

How about micro-? Without even checking, I bet several languages spell it mikro-.

And liter/litre…

Do the Danes and Norwegians really call a “meter” a måler? And check out the Lithuanian entry – skaitiklis (!).

Back to the OP … the decimeter (1/10 meter) could be used for a metric “hand”. As in “hand”, the unit for measuring the heights of horses (1 hand = 4 inches). The decimeter would be roughly 1/16" shorter at 3.937 inches.

No. That’s a “meter” in the “gas meter”, “multimeter” sense (although funnily enough "multimeter"s are called "multimeter"s). The measuring unit is a “meter”.

An etymologically founded translation of “måler” would be “measurer”, and it’s also used in words such as “landmåler” - land-measurer (i.e. surveyor).

In my personal experience, in South Africa (which metricated 50 years ago) the only prefixes in use here are the multiples of 1000 - i.e. micro/milli/kilo/mega - with the notable exception of the centimetre which is used about as commonly as the millimetre. But we don’t, for example, use centilitres or deci-anything. We do sometimes use hectares for land area.

Thanks for the correction – that happens to also be the case with the Lithuanian entry. I should have cross-checked with the Norwegian and Lithuanian Wikipedia entries for the SI unit.

The decimeter (Dezimeter) is totally a thing in German.

Well, in the different European Countries the prefixes are normally used in the local language, not in English, and in German at least we talk of Hektoliter, Hextare and Dekagramm spelled with a k.

Decigrams are absolutely a thing in Hungary. They’re commonly used to list quantities of ingredients in recipes. Ditto for decilitres.

Don’t you mean dekagrams? I don’t recall seeing decigrams in Hungary – that’s an awfully small unit (1/10 of a gram.) Dekagrams are common (or just “deka” in conversatoin as in Húsz deka sajtot, kérek “I’d like twenty deka(grams) of cheese.” )

You’re right; I’d mixed up the two prefixes.