I had a question about indices on a table and I put it up on Stack Overflow. I got my answer, but someone changed the word indices to say indexes.
We know that the plural of Index is Indices, but we also know that almost everybody prefers the "wrong" word.
What are some other "wrong" terms like this that really shouldn't be, but are overtaking their "correct" counterparts?
"Indices" is the mathematical formulation whereas in publishing they use "indexes" (which is probably why so many people in IT consider "indices" to be more correct than "indexes").
I think that a table index is analogous to an index in a book rather than an exponent in maths, so the publishing variant is the appropriate plural to use in this context.
Furthermore, at least in Oracle, the data dictionary views are called DBA_INDEXES, ALL_INDEXES and USER_INDEXES. It is usually a good idea to employ the same terminology which the domain uses.
Most people don't know that "data" is the plural and "datum" is the singular. How often have you heard "a single data point?"
But then again, even those of us who do know think it sounds goofy and hardly ever say it.
Language is mutable and "datum" might be on its way to becoming archaic by popular decree!
Summarizing answers here and elsewhere:
Both are widely used as the plural of index in English. The Latinate indices is more prevalent in scientific and mathematical contexts, as in the (subscripted) indices of array in a formula. But indexes appears to be on the rise, relatively stronger in publishing ('periodical indexes') and American English.
Some see a value in using indices uniquely for the plural of the noun index, as opposed to the 3rd-person singular present tense indexes of the verb index. ("He indexes all the TPS reports, you can find those indices in the circular file.")
Some perceive a small shading of difference between simple numerical-offset array indices and the more sophisticated data structures of database indexes or full-text indexes. ("The indexes were corrupted because the update code has an off-by-one error in its indices.")
These distinctions are sufficiently subtle that they're likely only maintainable within a tight-knit community of practice which documents & enforces their preferences, as if in some local & authoritative style guide.
Specifically when naming variables in code:
Using indexes has the often-desirable property that a simple grep search for index will also find that pluralization. When looking for indirect ways in which the same offsets might be referenced, that can be helpful.
target_index = 0
indexes[target] = 0
indexes['target'] = 0
target = len(indexes)
indices doesn't have this property, so I prefer to use indexes in code.
According to webster.com, both "indexes" and "indices" are correct; "indexes" is listed first.
That said, since "indices" was entirely correct to begin with, I don't really think it was appropriate to edit it and replace it with "indexes".
How about a reverse answer:
Too many people stubbornly (or maybe pendantically, or ignorantly?) insist on using the word "Octopi." "Octopus" originates from Greek, so the whole "us to i" for plurals paradigm doesn't exist. Some folks will even correct you if you say "octopuses," which is the correct English plural.
Not to judge, but I notice the folks who say 'octopi' are generally the same ones who insist on 'datum' and 'indeces' ;)
This has been discussed on other places as well. The English Stack Exchange cites the Oxford Dictionary to explain that both is valid:
plural of index: indexes or especially in technical use indices
The plural of index is usually spelled indexes, but can also be spelled indices (as in the original Latin) in subjects like science and medicine.
This page makes a good point by suggesting to use "Indices" as plural for the noun to distinguish it from the verb.
Summary
So all up I would say in technical context and writing - which is closer to science - and to distinguish it from the verb "Indices" is preferred in database speak.
Collins accepts both (http://www.collinsdictionary.com/dictionary/english/index) but in the French-English dictionnary (http://www.collinsdictionary.com/dictionary/english-french/index), it uses
grammarist.com considers indexes as the North-American variant.
This is just a continuation of the kilobyte/megabyte/gigabyte discussion. The English language is continuously evolving, and a dictionary isn't a book of rules to be followed, its a snapshot of how the language is used at that point in time. If we chose to use a word differently, then Webster better keep up.
Indices (coming from Latin) are used in scientific work, but otherwise indexes are used. So the use of indexes is correct in this case.
From Indexes versus indices (my emphasis):
... the standard English way of marking the plural, using -s or -es, has progressively been taking over ...This is why we now prefer crematoriums to the Latin crematoria and forums to fora, though the Latin plurals are still regularly used by some writers.
Indices has survived in scientific work, especially in mathematics. ... The usual plural is indexes, which first appeared in the seventeenth century.
