- A unit of measure equivalent to 10,000 meters.
There exist several unit prefixes that are used like the SI prefixes but are not part of the SI system.
Some of these prefixes were never part of any actual system of measurement. A few were proposals that were rejected. None is in common use, and many of the powers of ten they represent are covered by SI prefixes. Sometimes a prefix is simply mistaken; dk has been passed off as an abbreviation for deka.
One such prefix is bronto, used in the fake term brontobyte. References on the World Wide Web suggest meanings of the bronto prefix to be variously any of 1015, 1021, 1024, or 1027. SI has already produced standard prefixes for 1015 (peta), 1021 (zetta) and 1024 (yotta).
Proposed and unofficial prefixes
There are many other unofficial prefixes. Some of them appear to come from numerical Greek roots indicating the power of 1000 the prefixes mean. Others are based on the names of the Marx Brothers. These prefixes are:
Some prefixes were used in older versions of the metric system but are not part of the modern metric system, the SI.
The prefixes 'myria' (ma or my, for 10000) and 'myrio' (mo, for 1/10000) came from the Greek μύριοι (mýrioi) 'ten thousand'. Part of the original metric system adopted by France in 1795, they were not retained when the SI prefixes were agreed internationally by the 11th CGPM in 1960.
They were rarely used, though the myriameter (10 km) is occasionally encountered in 19th-century train tariffs. In Sweden (and possibly elsewhere), the myriameter is still very common in everyday use (although not recognized or used officially). In Swedish this unit is called 'mil', sometimes causing confusion when Swedes use the English word 'mile' (incorrectly) as a direct translation.
Of units customarily used in trade in France, the myriagramme (10 kg) was the metric replacement for an avoirdupois unit, the quarter (25 pounds). (cp. Myriogramme, a genus of seaweed)
In Isaac Asimov's novel Foundation and Empire, there is a mention of the "myria-ton". Also obsolete are metric double prefixes, such as those formerly used in micromicrofarads, hectokilometres, micromillimetres.
- Proposal to extend system of units from 10−63 to 1063
- BBC article suggesting that a brontobyte is 1027 bytes
- Sybase article suggesting that a brontobyte is 1024 or 1027 bytes (Note article's table a few pages down. Note also it mistakenly places 1 terabyte = 1,000 megabytes. It should be 1 terabyte = 1,000 gigabytes. Also yottabyte is shown incorrectly as zottabyte. With those corrections, it also is clearly 1027.)
- Article suggesting that a brontobyte is 1021 bytes
- Article suggesting that a brontobyte was 1015 bytes before the creation of the prefix peta- (Article is of dubious authority... suggests that Greek letters ν, π, and φ are SI prefixes for nano-, pico-, and femto-, instead of n, p, and f.)
- Article suggesting that brontobyte is 1027 bytes
- Moerner Lab Single-Molecule Research Page (Jokingly defines 1 guacamole = 1 / (Avocado's number) of moles. Scientific paper with reference)
- Jargon file entry for "quantifiers" Claims that groucho, harpo, grouchi, and harpi (based on the Marx Brothers' names) have gained the general approval of Usenet.
- vendeka.org website Support for vendeka = 1033
- Final Answers: Measurement and Units Large table of units
myriameter in Dutch: Prefix niet behorend tot het SI
myriameter in Japanese: 非SI接頭辞
myriameter in Polish: Niestandardowe przedrostki jednostek miar
myriameter in French: Préfixe d'unité non-SI