Arikah Map

Non-SI unit prefix

(Redirected from Non-SI unit prefixes)

There exist several unit prefixes used like the SI prefixes, but that are not part of the SI system.

Some of these were never part of any actual system of measurement. A few were proposals that were rejected. None are in common use, and many of the powers of ten they represent are already taken 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).

There are many other unofficial prefixes. Some of them appear to come from a numerical Greek root indicating the power of 1000 the prefix means. These prefixes are as follows:

Prefix Purported meaning
udeka- (U) 1036
udekta- (U) 1036
una- 1033
vendeka- (V) 1033
weka- (W) 1030
wekta- (W) 1030
decetta- 1030
dea- 1030
grouchi- 1030
nea- 1027
xenna- (X) 1027
xenta- (X) 1027
novetta- 1027
harpi- 1027
lotta- (L) 1027
nova- (N) 1027
otta- 1024
hepa- 1021
ento- 10−21
fito- 10−24
syto- 10−27
xenno- (x) 10−27
novemo- 10-27
harpo- 10-27
lotto- (l) 10-27
novo- (n) 10-27
millikan- (mkan) 10-27
tredo- 10−30
weko- (w) 10−30
decemo- 10-30
groucho- 10-30
revo- 10−33
vendeko- (v) 10−33

Contents

Obsolete prefixes

There are some prefixes that were used in some older versions of the metric system but that are not part of SI. The prefixes 'myria' (ma or my, for 10000) and 'myrio' (mo, for 1/10000) came from the Greek μύριοι (mýrioi), meaning both ten thousand and "an indefinite large number". There is no Latin equivalent. Adopted by the French in 1795, they were not retained when the SI prefixes were agreed internationally by the 11th CGPM in 1960.

Also obsolete are metric double prefixes, such as those formerly used in micromicrofarads, hectokilometres, micromillimetres, and so on.

Proposed systems

A proposal by Jim Blowers describes the naming scheme as follows:

zetta is Z + -etta, which is an alteration of septi-, meaning 7, as 21 is 7 groups of three. yotta is Y + -otta, an alteration of octo-, meaning 8. The pattern here is that we go backwards from the beginning of the alphabet, starting with z and y, and we follow it up with an alteration of the Greek or Latin for the next number. According to this pattern, the next ending should be xona-, since X comes before Y in the alphabet, and 9 is noni- in Latin. Similarly, 1030 should be weka-, since W precedes X and 10 is deka in Greek.

Factor Name Symbol Factor Name Symbol
10-1 deci- d 101 deca- da
10-2 centi- c 102 hecto- h
10-3 milli- m 103 kilo- k
10-6 micro- μ 106 mega- M
10-9 nano- n 109 giga- G
10-12 pico- p 1012 tera- T
10-15 femto- f 1015 peta- P
10-18 atto- a 1018 exa- E
10-21 zepto- z 1021 zetta- Z
10-24 yocto- y 1024 yotta- Y
10-27 xonto- x 1027 xona- X
10-30 wekto- w 1030 weka- W
10-33 vunkto- v 1033 vunda- V
10-36 unto- u 1036 uda- U
10-39 trekto- td 1039 treda- TD
10-42 sotro- s 1042 sorta- S
10-45 rimto- r 1045 rinta- R
10-48 quekto- q 1048 quexa- Q
10-51 pekro- pk 1051 pepta- PP
10-54 otro- o 1054 ocha- O
10-57 nekto- nk 1057 nena- N
10-60 mikto- mi 1060 minga- MI
10-63 lunto- l 1063 luma- L

There have also been proposals to use the units of one of these systems with prefixes of a different base than ten, e.g. binary, duodecimal or hexadecimal.

Categories


Prefixes

Find

Find

Find