This week, Ronnie Cohen takes issue with an example of American exceptionalism.
Most metric prefixes and units are spelled the same way throughout the English-speaking world. However, there are a few notable exceptions where the Americans use different spellings from the rest of the English-speaking world. The exceptions are:
- metre (US spelling: meter)
- litre (US spelling: liter)
- tonne (US spelling: ton) – this refers to the metric tonne of 1000 kg
- deca- (US spelling: deka-) – a metric prefix meaning a factor of 10
While the US spellings are used by the Americans, the British spellings are used by all major English-speaking countries and the rest of the Commonwealth, the European Union (EU), the World Trade Organisation (WTO), International Standards Organisation (ISO), the North Atlantic Treaty Organisation (NATO), International Olympic Committee (IOC) and the International Bureau of Weights and Measures (BIPM).
This issue matters for use in legal contracts in all countries where international businesses operate. There are also implications for international websites and publishing where separate versions of common materials or information must be produced for American and non-American readers.
The spelling “metre” always refers to the fundamental unit of length in the metric system. According to the Oxford English Dictionary (OED), it comes from Old English, reinforced in Middle English via Old French “metre”, Latin “metrum” and originally from Greek “metron”, meaning measure. From this word, we derive words and their spellings related to the metric system and general measurement terms such as:
- metronome (OED: A musician’s device that marks time at a selected rate by giving a regular tick.)
All the words listed above are related to “metre” and are never spelled meter-, always metr-.
The meter is normally used for measuring devices in all parts of the English-speaking world. The names of all kinds of measuring device end in -meter. According to the OED, meter comes from Middle English, that in the sense of “person who measures”, it is derived from “METE” + “-ER”.
It is often useful to distinguish between units of lengths and measuring devices. The “Spelling metre or meter” document by Pat Naughtin gives some useful examples (see link at the bottom of this article). It is a standard feature of English spelling to use different spellings for words that sound the same to convey meaning (e.g. wait/weight, whole/hole, etc.). It is also a hallmark of the English spelling system to retain the original spellings for foreign words (e.g. double, paella, pizza, spaghetti, etc.). The distinction between the “metre” spelling for distance and the “meter” spelling for measuring devices is especially useful for distinguishing between micrometre for a millionth of a metre and micrometer, an instrument for measuring extremely small distances. They are even pronounced differently. Micrometre is pronounced with emphasis on the first syllable whereas micrometer is pronounced with emphasis on the second syllable.
According to the OED, the metric unit of volume or capacity, the litre, comes from French, alternative of “litron”, an obsolete measure of capacity, via medieval Latin, from Greek “litra”, a Sicilian monetary unit. The OED lists the noun “litreage” as a derivative word of litre, interestingly with no variant spelling (i.e. “literage” spelling does not exist).
The “tonne” spelling is only used for the metric tonne, a weight equal to 1000 kg. The “ton” spelling is normally used for various types of non-metric tons. Some relate to mass and others relate to volume or capacity. The OED lists the following tons for which the “ton” spelling is used:
- long ton
- short ton
- displacement ton
- freight ton
- net ton or register ton
- gross ton
Each item in the list has a different meaning. The Americans also use the “ton” spelling for the metric tonne. When they write “ton”, they also need to write “metric” before “ton” to distinguish between the metric tonne and other tons. While the Americans do not use the “tonne” spelling, they still maintain the distinction between the “ton” and “tun” spellings. The OED lists “ton” as a word of Middle English origin and a variant of “tun” and says that both spellings are used for the container and the weight. If the Americans wanted to go for a phonetic spelling for the metric tonne, they would surely have opted for “tun”, which already exists as a valid English spelling, albeit used for other meanings. The “tun” spelling is used for large beer and wine containers and also for an imperial capacity measure equal to 4 hogsheads.
I did a quick online search to find out what other words ended in -onne then looked them up in the OED. I found the following entries in the OED:
- chaconne (pronounced sha-kon)
- cretonne (pronounced kre-ton)
For these words, there is no US variant spelling.
The “deca-” prefix does not just exist in the metric system. The “deca-” prefix, or “dec-” before a vowel, is a common English prefix used in many words for ten or for having ten. I found several examples of this prefix in the OED as shown in the table below:
|Word with Dec-/Deca- Prefix||OED Definition of Word|
|decade||A period of ten years.|
|decagon||A plane figure with ten straight sides and angles.|
|decahedron||A solid figure with ten plane faces.|
|decalitre||A metric unit of capacity, equal to 10 litres.|
|Decalogue||The Ten Commandments|
|decametre||A metric unit of length, equal to 10 metres.|
|decapod||A crustacean of the order Decapoda, with five pairs of walking legs (i.e. with ten legs), such as a shrimp, crab, or lobster.|
|decastyle||(of a temple or portico) having ten columns|
|decasyllabic||(of a metrical line) consisting of ten syllables|
|decathlon||An athletic event in which each competitor takes part in the same ten events.|
The only spellings I found in the OED starting with “deka-” were the US spellings “dekaliter” for decalitre and “dekameter” for decametre. According to the OED, the Americans also use “decaliter” and “decameter” spellings and also use “dkl” and “dkm” abbreviations for decalitre and decametre respectively. These abbreviations are not recognised or accepted by the BIPM. These abbreviations are presumably used by the Americans as a result of their use of the non-standard “deka-” prefix. Only “dal” and “dam” are accepted symbols for decalitre and decametre respectively. For all the other words in the table above, there is no variant “deka-” spelling. Hence, for consistency, it makes sense for the Americans to standardise on the use of the “deca-” prefix and abandon the “deka-” prefix.
Variant US spellings are based on the ideas of Noah Webster, the original author of the American dictionary that bears his name. The Americans went their own way in terms of spellings, probably to differentiate their newly independent country from the British and to help the American publishing industry. While Americans do not accept the -re ending for metre and litre, they accept this ending for numerous other words such as acre and ogre and to differentiate between timbre/timber. Here, I made the case for the Americans to use the standard spellings for metric units used by the rest of the English-speaking world and virtually all international organisations. It is not clear to me what they gain by using separate spellings from the rest of the world. However, it has implications for international businesses. They would need to produce separate labelling, manuals, web pages, contracts and other materials for the Americans and the rest of the English-speaking world. At Pat Naughtin has pointed out, the British (and international) spellings for metric units are universally accepted but the American spellings are not. In markets where they are not accepted, that could make contracts for international businesses operating in these markets null and void.