New SI prefixes and their etymology

Five months ago I wrote a post speculating about new SI prefixes. I said in this post There's no need for more prefixes; this post is just for fun."

Well, truth is stranger than fiction. There are four new SI prefixes. These were recently approved at the 27th General Conference on Weights and Measures. Here is the resolution (in French).

The new prefixes are:

• 10³⁰ quetta (Q)
• 10²⁷ ronna (R)
• 10^-27 ronto (r)
• 10^-30 quecto (q)

The names were the suggestion of Richard J. C. Brown. He gives seven desirable properties of new names:

1. The names should be simple and, if possible, meaningful and memorable.
2. The names should have some connection to the powers of 10³ that they represent.
3. The names should be based on either Latin or Greek as the most used languages previously.
4. Multiples should end -a' and sub-multiples should end -o'.
5. The symbols used should be the same letter for a given power of ten, in upper case for multiples and in lower case for sub-multiples.
6. Letters already in use for SI prefixes, SI units, other common units, or symbols that may otherwise cause confusion, should be avoided.
7. Following the precedent set recently, letters should be used in reverse English alphabetical order, suitably modifying chosen names, and skipping letters as appropriate.

OK, so how does that lead to the new prefixes? Point #4 explains the last letter of each prefix.

Brown says that the etymology of ronna and ronto is

Greek & Latin, derived from ennea' and novem', suggesting 9 (ninth power of 10³)

and that the etymology of quetta and quecto is

Latin, derived from decem', suggesting 10 (tenth power of 10³).

That's quite a stretch.

The largest prefix had been zetta and yotta, so Brown wanted letters that came before Y in the alphabet. P was already used (peta and pico) and the next two unused letters were Q and R. So the prefixes for 10³⁰ and 10²⁷ begin with Q and R.

Presumably ronna uses an O because yotta had an O for the second letter. And the next letter N comes from the N's in ennea and novem.

It seems quetta used the Q sound because Q was the next letter available, and an allusion to the hard C in decem. The etta" part is reminiscent of zetta.

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