An exercise in astrolexicography

Plutoids and plutinos . . .

When the former planet Pluto was demoted to the status of “dwarf planet” fairly recently, two new words were defined by the International Astronomical Union: plutoid and plutino. If you ask me, these would be damn good words whatever they meant: they belong to that group of words which seem to exist as much because they’re fun to say as because they’re needed.

Several weeks ago one of my contacts on Twitter, @Exoplanetology, came up with the word exoplutoid, meaning a plutoid in a planetary system other than our own.

Should you wish to know, a plutino is an object which, like Pluto, orbits the Sun twice for every three orbits made by Neptune. (This is called a 2:3 resonance, and the object remains trapped in that orbit.) A plutoid, roughly speaking, is simply a dwarf planet which orbits the Sun further out than Neptune does.

I suppose an exoplutoid might be a dwarf planet in another star system, further from its star than the last convincing planet.

Nice words. Are there more?

Plutonyms in the dictionary

Let’s proceed with caution. A look at the dictionary reveals that a number of pluto- words already exist. Furthermore, not all of them are anything to do with Pluto. Plutocrats, being plutocratic in a plutocracy, get their name from the Greek word ploutos, which means wealth.

In geology, plutonic relates to rocks which have solidified from a molten state at the fiery depths associated with the god Pluto and his underworld, and a pluton is a “body of instrusive igneous rock”. Geology also uses the word plutonism in this connection.

In chemistry, the element plutonium has nothing to do with plutonism; the elements uranium, neptunium and plutonium take their names (rather nicely) from Uranus, and Neptune and Pluto, which were all planets at the time.

Plutogenous neologisms

Given the existence of all these words already, are we to conclude that Pluto has contributed all it can to the English language? I think not!

There are still plenty of Pluto-related situation requiring words. Some of the situations are more “serious” than others. But all need words, and it is my pleasure to present them to you. They are grouped by function rather than alphabetically. Use and enjoy.

similar in material or structure to Pluto.
exoplutoid, exoplutino:
a body in another planetary system analogous to a plutoid or plutino in ours.
originating from, or generated or caused by, Pluto and its status. For example, plutogenous fisticuffs might result from a heated discussion about its classification. See plutonym, below.
removal of Pluto or a Pluto-like object, e.g. from a list of recognised planets or (as a more advanced engineering project) from a planetery system
relating to the creation of Pluto-like objects, i.e. to plutogenesis.
a word created with reference to Pluto and its status; that is, one which enters the language as a plutogenous neologism.
the study of plutonyms.
the creation of a dictionary or glossary of plutonyms
an inability to remember what Pluto is officially classified as these days.
suffering from or relating to plutamnesia.
someone who suffers from plutamnesia.
1. condition of accidentally using the wrong plutonym, e.g. calling a plutoid a plutino or describing plutogenous situation as plutogenic. The corresponding adjective is paraplutotic.
2. erroneous identification of an object as Pluto.

Got any more? Post them here and I’ll do the plutolexicographer’s job of gathering them together, time and energy permitting. Especially if they’re good.

8 responses to “Plutonymics

  1. Thank you for a wonderful infotaining article on an astronomically humorous issue of our day – Pluto and all the plutonyms and neologisms that arose from it all!
    Thanks for the mention. It’s much appreciated!

  2. As a Plutophile, I emphasize that Pluto is NOT a former planet. Only four percent of the IAU voted on this, and most are not planetary scientists. Their decision was immediately rejected by hundreds of professional astronomers led by Dr. Alan Stern, Principal Investigator of NASA’s New Horizons mission to Pluto. So this is very much an ongoing debate. A big problem is that the IAU definition states that dwarf planets are not planets at all! This is inconsistent with the use of the term “dwarf” in astronomy, where dwarf stars are still stars, and dwarf galaxies are still galaxies.

    All of the Pluto related words originate with the name of the Roman god Pluto, ruler of both the underworld and wealth.

    For some additional Pluto words, as a writer advocating the overturning of Pluto’s demotion, I drive a car with a bumper sticker that reads “Pluto is a planet,” which I have nicknamed the Plutomobile. My cell phone has a picture of Pluto and also reads “Pluto is a planet,” which is why I have nicknamed it the Plutophone.

    And I am often referred to by friends and online as “Plutogirl.”

    • Thanks for the background on the IAU decision. For myself, as a word lover I’m unhappy about the inconsistencies in the language (surely dwarf qualifies planet, and so a dwarf planet should indeed mean a type of planet, not something else). As a science enthusiast I’m unhappy about the arbitrariness of the definitions, which seem not to be a natural reflection of the situation they refer to.

      A feature of word etymologies is that what one thinks one knows often turns out to be true, so I should have checked before posting how Pluto might be related to plutocracy and its derivatives. Well I’ve now done so, and the situation seems to be:

      Plutocracy is derived from Greek ploutokratia.
      Ploutokratia itself comes from Greek ploutos meaning “wealth”, and kratos meaning “strength, authority”.
      The Roman god Pluto was originally the god of certain metals. These were mined from the ground (so he became god of the underworld), and used as money (so he became god of wealth).
      Pluto’s name is thought to be derived from Greek ploutos, for wealth.

      If Pluto was god of metals before he was god of wealth, then this raises the question of what his name was in the meantime, or if he was already named after ploutos, what that word meant. My guess is that it referred to the metals, so it would still be logical for Pluto’s name to be derived from it. But that’s just a guess and if anyone else feels like doing the work of finding out, please do!

      So although I wasn’t strictly accurate to say plutocracy has nothing to do with the god Pluto, neither is it derived from him. The Roman god, and the English word, are separately derived from the Greek word ploutos.

      The derivation from ploutokratia comes from the Oxford English Dictionary, which I trust as an authority. The information about Pluto might be on dodgier ground, being from Pluto’s Wikipedia entry, but I’m happy to believe it for now😉

  3. I too am puzzled by the inconsistency: dwarf stars are still stars, and dwarf galaxies are still galaxies. Why does IAU refuse to recognize dwarf planets as planets? Simply tweaking their decision to be consistent with astronomical terms using “dwarf” would save us all the confusion. I know it’s a lot of hard work to open the floodgates to planethood, but it’s exciting!
    Common sense really dictates that dwarf planets are planets. If Pluto is a dwarf planet, it is therefore a planet.

  4. How about:

    plutojection – the reclassification of something to be a subcategory of what it used to be considered, confusing people into believing that it is no longer in its supercategory even though it clearly should still be considered as such.

    …or something like that. Or maybe something completely different. The word just jumped into mind and I caught it, unsure of what to do with it.

    My idea was inspired by the Latin jectare/jactare, to throw, so if you can come up with another meaning that fits it better, please do!

    • I like plutojection! I can see your definition (being thrown out of its category) but to me it sounds like what happens to a plutoid or plutino (or exoplutoid or exoplutino) which has an unfortunate gravitational encounter and gets flung out its planetary system – maybe this has already happened to some of ours? Or it could be something small getting thrown out by Pluto, if that’s remotely possible.

      Edit: And now I’ve realised that it could additionally be a psychological term: the particular kind of dejection experienced when one has been suddenly demoted.

  5. Can i say that i’ve just been “Plutoed”?
    (Somebody just stole the bike I use to go to work.) I guess it’s the same feeling when something gets taken away from you🙂

  6. Ah, now I’m glad you asked about plutoed. I’d forgotten that the American Dialect Society voted it Word of the Year for 1996 There is even a website “for people who have been plutoed”, taken to mean having suddenly lost status. See also the contradictory definitions at

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