Prepone is a great word - it's the opposite of postpone. When you prepone a meeting, you change its scheduled time so that it occurs sooner than originally planned. Has this usage spread beyond India? Would other English speakers understand it?
IN India, people created the word “prepone” as the obvious opposite of postpone. On the Internet, a form of cyber-English has sprouted with such words as “net-surfing.”
(I hope it surprises no one that this citation is from 1995—eons ago in Internet time).
More recently, in 2008 the Monitor published this article discussing prepone in much more detail.
So it does not appear that prepone has much currency outside of India. I have heard it in my day-to-day business on occasion here in the United States in the software development industry—from my colleagues from India.
The New Oxford American Dictionary I had on my Mac Mini didn't report prepone as an existing word. The Oxford Living Dictionaries says that the meaning of prepone is:
[Indian] bring (something) forward to an earlier date or time.
One of the examples it shows is the following.
The publication date has been preponed from July to June.
It also says its origin is early 20th century.
Wiktionary also reports it is only used in India (or that is chiefly from that country).
OED explains that the etymology is from the classical Latin word praepōnere:
pre- and pōnere- to place
This gives the word its (now) obsolete meaning of to place in front of or to set before. The later use of this word to refer almost exclusively to placements in time is said to be most frequent in Indian English.
Thus contrary to popular belief it is not an Indian neologism but has Latin roots similar to the well known antonym.
Prepone is an interesting word: For many years, it existed in a period of stagnation where it only occasionally popped up. Then, it made its way into Indian English, found its semantic niche, got put in lists of Indianisms, and
as a result it exploded in popularity continued to be used in Indian English and get put on lists of Indianisms. Prepone is going nowhere.
Over the years, it has been both maligned and adulated, described as both 'quaint' and 'apt' in the same quote, and made a number of cameo appearances in books that teach you to 'not make mistakes.' On the other hand, it's been praised for its usefulness, and Fowler's says that it "deserves to be more widely used than it is."
Even those who condemn it cannot bring themselves to do so completely:
The same tolerance is not extended so readily to primary cultures and communities, where the language is used in the conduct of everyday social life. Lexical innovation here, equally motivated by communal requirement, is generally dis- missed as dialect. Take, for example, the two words depone and prepone. The first is a technical legal term and therefore highly respectable. The second, prepone, is not. It is an Indian English word of very general currency, coined to contrast with 'to postpone'. To postpone an event means to put it back, to prepone an event is to bring it forward. The coinage exploits the morphology of English in an entirely regular way. It is apt. But it is also quaint. An odd Indian excrescence: obviously non-standard. And yet there is clearly nothing deviant in the derivational process itself and, indeed, we can see it at work in the formation of the related words predate and postdate. But these are sanctioned as entirely ordinary, proper, standard English words. What, then, is the difference? The difference lies in the origin of the word. Prepone is coined by a non-native-speaking community, so it is not really a proper English word. It is not pukka. And of course, the word pukka is itself only pukka because the British adopted it.
From World Englishes- 2003
And at the same time, most substantial mentions of the word soon take a bit of a pondering, philosophical turn:
What does it mean to talk about English as an international language anyway? This is a question I shall take up in a later chapter, but meanwhile there is a more delicate difficulty to deal with.
Consider the word 'prepone'. This does not occur in current British usage and never has occurred in the past. [However] it is apparently quite commonly attested in India. Is it proper English?
In one respect it could not be more proper, for it is impeccably well-formed according to the standard rules of English morphology. It is indeed a good example of the productive exploitation of the generative power of grammar which is said to be a defining feature of linguistic competence, and this presumably applies as much to the morphological formation of words as to the syntactic formation of sentences. 'Prepone', then, is properly formed. It is also semantically apt in that it contrasts precisely with 'postpone' to denote the advancing as distinct from the deferring of an event. A meeting can obviously be brought forward, preponed, just as it can be put back, postponed. The word neatly fills a lexical gap. All that standard British English has to offer instead is the rather cumbersome phrase 'bring forward' which (to the confusion of learners) does not even allow the entirely reasonable contrasting phrase 'take backward'.
So is 'prepone' to be recognized as real English? After all, not only does it, like the Lewis Carroll verbal inventions referred to earlier, conform to the encoding rules of English, but, unlike those of Carroll, has actually been coined to meet a communicative contingency and is given the sanction of social use. In this respect it is like the innumerable other examples of lexical coinage that have been devised to deal with new technology over recent years, and which have been readily received into the language. What is more, it might be pointed out, in its innovative use of linguistic resources, it resembles the kind of language which Shakespeare wrote, and this is usually highly commended; indeed, as we have seen, it is considered proper by definition.
From Defining Issues in English Language Teaching- 2003
Yet for all this existential huffing and puffing and questioning of what makes a word a native word, and for all the books and articles that acknowledge its utility, the fact remains: prepone is going nowhere. Sure, there's this pleasant little curve on Ngrams (which peaks around the time you asked this question) and sure, most of the world that's read about Indianisms knows of it, but nobody is really using it in non-anecdotal contexts. There is no ambiguity or confusion as to what you're saying, but equally, there's little established precedent in it being used naturally in non-subcontinental publications.
Merriam-Webster is 'watching' the word:
"The modern Indian prepone has a lot going for it: it’s easy to say and spell, it’s made of familiar parts, and it’s an efficient way to say something for which we have no other word.It may well catch on in the rest of the English-speaking world."
Wonderful! But is the individual who wrote that article using it? I'd guess: no. This is just speculation, but my feeling is that all these articles have exotified it to the extent that the word has been branded as an Indianism. There are few instances of it appearing organically outside of India.
I can't explain why it hasn't caught on, and I of course could be wrong that it won't. But it isn't catching on right now, it hasn't really caught on in the decade since you asked this question, and my guess is that this won't be changing.