|(English) This is an essay. It expresses the opinions and ideas of some Wikimedians but may not have wide support. This is not policy on Meta, but it may be a policy or guideline on other Wikimedia projects. Feel free to update this page as needed, or use the discussion page to propose major changes.
Ideally, constant effort keeps vocabulary manageable for the casual user, and under 4000-5000 words for introductory articles - those with the shortest names. The three billionth user comes to the wiki in 2007 with English as a second language, very little time and a low bandwidth connection, and walks away with the most useful description of an ecologically-sensitive garden they could possibly have got in that time...
What's wrong with this picture? What realistically can we do about overly complex vocabulary? It takes 1900 words to define the 4000 most common English w:idioms - so what are the worst cases regarding vocabulary creep? How big can we let it get? Highly educated people in the world tend to have at most 15,000 word vocabularies - how to handle profession jargons?
Most importantly, how to keep a concordance that shows us how meanings are evolving?
Please be aware of http://simple.wikipedia.com/ , the "Simplified English" version. Perhaps we should send your 3 billionth user there.
For technical jargon, they should be definied within the context of the article. People more or less just do this naturally. And the rest, dictionaries are easily accesible.
If you want to see why vocabulary creep is not a problem, check out the Oxford English Dictionary. There is a whole lot of words in there, but many of them are never used. They just drift out of the language by themselves.
My initial thought is that as articles get deep or detailed in technical or overly lofty language often used by specialists or people intimately familiar with the subject that an attempt to write a simplied overview to introduce the article or this could move to a separate article or wikipedia and referenced/linked. User:mirwin
See also reading level.