"redices" and "indices"
Kragen Javier Sitaker
kragen at pobox.com
Mon Apr 30 03:37:02 EDT 2007
I recently corrected someone who used the term "redices" to mean
"reducible expressions" (in the context of the lambda-calculus and
similar formal systems):
"redices" is not the plural of "redex". If there were a Latin word
"redix", it might pluralize as "redices", but there isn't, and
"redix" is different from "redex" anyway.
He pointed out:
I think "redices" is fairly common use, as a googling
confirms. . . . What makes you think "redices" isn't the plural of
"redex"? How are you with "indices"?
I had to admit that he was right about "index" not being "indix". I
don't speak Latin myself, but a friend of mine who does explained to
me that "index" and "indices" are the nominative singular and plural
of "index", a regular third-declension Latin noun. Charlton Lewis's
Latin dictionary has the following entry for it :
index dicis, m and f [in+DIC-] , one who points out, a discloser,
discoverer, informer, witness: falsus, S.: haec omnia indices
detulerunt.-- An informer, betrayer, spy: vallatus indicibus:
saeptus armatis indicibus: silex, qui nunc dicitur index,
traitor's stone, O.--An index, sign, mark, indication, proof:
complexus, benevolentiae indices: vox stultitiae: auctoris
anulus, O.: Ianum indicem pacis bellique fecit, L.--A title,
superscription, inscription: deceptus indicibus librorum: tabula
in aedem cum indice hoc posita est, L.--A forefinger, index
finger: pollex, non index: indice monstrare digito, H.
I don't know the etymology of the term "redex" for certain, but it
means "reducible expression", and is therefore an originally English
word, not a Latin loanword. It doesn't appear in the Oxford English
English is somewhat unusual in that it often imports irregular
pluralizations of loanwords along with the original loanwords --- thus
we have mujahedin, Taliban, tableaux, criteria, cherubim, axes, and
bacteria, rather than *mujahids, *Talibs, *tableaus, *criterions,
cherubs, *axises, and *bacteriums.  This adds to the confusion of
irregular plurals already natively present in English, things like
"oxen", which was in Old English, coming from Proto-Germanic and
ultimately from Proto-Indo-European. 
As illustrated above, there are many cases in which the regular plural
form is considered incorrect by almost everyone, but there are other
cases where use of the irregular "classical" form is a way to show off
the speaker's erudition; I think "index" and "cherub" are such
examples. Both "indexes" and "cherubs" are legitimate English, but
"indices" and "cherubim" are ways to demonstrate your erudition, and
perhaps your knowledge of Latin and Hebrew. Damian Conway's article
"An Algorithmic Approach to English Pluralization"  lists several
Showing off one's knowledge may be thought to demonstrate an arrogant
attitude of superiority, if those you're talking to don't share that
same knowledge, or to demonstrate that you belong in the group, if
they do. However, in either case, it's worse if the folks you're
talking to know that the knowledge you're showing off is wrong.
The Jargon File mentions deliberately irregular pluralizations in
hacker jargon :
Further, note the prevalence of certain kinds of nonstandard
plural forms. Some of these go back quite a ways; the TMRC
Dictionary [from the 1950s?] includes an entry which implies that
the plural of 'mouse' is meeces, and notes that the defined plural
of 'caboose' is 'cabeese'. This latter has apparently been
standard (or at least a standard joke) among railfans (railroad
enthusiasts) for many years.
On a similarly Anglo-Saxon note, almost anything ending in 'x' may
form plurals in '-xen' (see VAXen and boxen in the main text)
[following "oxen"]. Even words ending in phonetic /k/ alone are
sometimes treated this way; e.g., 'soxen' for a bunch of
socks. Other funny plurals are 'frobbotzim' for the plural of
'frobbozz' (see frobnitz) and 'Unices' and 'Twenices' (rather than
'Unixes' and 'Twenexes'; see Unix, TWENEX in main text). But note
that 'Unixen' and 'Twenexen' are never used; it has been suggested
that this is because '-ix' and '-ex' are Latin singular endings
that attract a Latinate plural. Finally, it has been suggested to
general approval that the plural of 'mongoose' ought to be
The pattern here, as with other hackish grammatical quirks, is
generalization of an inflectional rule that in English is either
an import or a fossil (such as the Hebrew plural ending '-im', or
the Anglo-Saxon plural suffix '-en') to cases where it isn't
normally considered to apply.
This is not 'poor grammar', as hackers are generally quite well
aware of what they are doing when they distort the language. It is
grammatical creativity, a form of playfulness. It is done not to
impress but to amuse, and never at the expense of clarity.
One might also speculate that hackers do this to poke fun at those who
think that knowing Latin declensions makes them smart.
Other, non-hacker occurrences of the same playful misapplied Latin
pluralization have been reported, such as "grimi" for "grimaces" or
"waitri" for "waitresses". 
Back to "Redices"
So I can think of six likely interpretations a listener might arrive
at when they hear "redices" used as the plural of "redex":
1. The speaker is trying to demonstrate that they're better-educated
than I am, but they are failing, because they don't know enough
Latin to know that "redex" isn't a Latin word. Therefore, they are
not only arrogant but unskilled and unaware of it .
2. The speaker is trying to demonstrate that they are as well educated
as I am, but they are failing, because they don't know enough Latin
to know that "redex" isn't a Latin word. Therefore, they think
they are not worthy of associating with me, because they think they
would need to have a classical education in order to be so, but
they clearly don't have it. Furthermore, they are unskilled and
unaware of it.
3. The speaker uttered an incomprehensible word. They must have a
bigger vocabulary than I do; maybe they are smart and I should
listen to them more carefully.
4. The speaker uttered an incomprehensible word. They must be talking
5. The speaker is playfully forming a nonstandard plural.
6. This word "redex" I haven't heard before must be a Latin word, and
"redices" is either its only correct plural or a correct show-off
I suspect that explanation #5 is the correct explanation of the term's
origin, and it's prefigured by the "Unices" and "Twenices" examples
from the Jargon File , but I intend to avoid the use of "redices"
except in clearly playful contexts because of the possibility of
interpretations #1, #2, #4, and especially #6, which will make it more
difficult for the listener to discover the correct derivation from
"reducible expression". Maybe this is just me taking myself way too
If you correct people who are using "redices" (as I did), you run the
risk of a similarly hazardous gamut of responses.
1. Why is he trying to show off his knowledge? Doesn't he know
"redices" is a playful invention? He must be not only arrogant but
unskilled and unaware of it.
2. I've always heard "redices" as the plural of "redex". Have I been
looking dumb all these years?
These references are not intended to assign credit; they're just here
so you can dig deeper if you're interested.
 Charlton Lewis, "An Elementary Latin Dictionary", 1890, ISBN:
 Letter from Dr. Lim Chin Lam, Penang, to The Star of Malaysia
It must be noted that the above nouns have been adopted (or
borrowed or hijacked) from other languages and normally retain the
singular and plural forms in their original language.
 Douglas Harper's Etymonline Online Etymology Dictionary entry "ox"
 Jargon File 4.2, dated 2000-01-31, attributed to a large
collection of hackers but currently enclosed by Eric Raymond, section
"Jargon Construction", subsection "Overgeneralization";
 "Unskilled and Unaware of It: How Difficulties in Recognizing
One's Own Incompetence Lead to Inflated Self-Assessments", by Justin
Kruger and David Dunning, published in the Journal of Personality and
Social Psychology, December 1999, Vol. 77, No. 6, 1121-1134
 "More False Latin", by John Algeo, American Speech, Vol. 41, No. 1
(Feb., 1966), pp. 72-74, doi:10.2307/453250
 "An Algorithmic Approach to English Pluralization", by Damian
Conway; this describes the algorithm in Lingua::EN::Inflect.
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