On stack overflow, I see that there is referred to Wikipedia a lot. However, I'm often not sure whether they are the definite authority for very specific software development related concepts. For example, I have recently looked for definitions of the terms web server/service and RPC/IPC, and the responses I get very often refer to Wikipedia (directly and indirectly).
Hence my question: which sources do you trust the most for definitions of software development jargon?
Personally I used to trust Wikipedia, and I still read it to get an idea about the subject. But definitely books are better choice. Because they not only have a "compressed" explanation but also provide an examples and give broader description. As professors of my university say, don't trust wikipedia, search for an authorized source. For example a huge information about web service technology you can find in the book Building Web Services with Java - Making Sense of XML, SOAP, WSDL, UDDI - 2nd Edition 2005. It contains information you'll never find in Wikipedia or even in Google (Unless you'll find this book using it ;) ). Hope this helps.
Google and technical & non-technical software development books.
"A Story Culture" may be a useful read for you as you want something other than a dictionary, IMO. You want something with the knowledge and wisdom of the topic rather than simply what does this mean. For example, there are a couple of blog posts about Technical Debt that I really like to use for reference about the subject, one from Steve McConnell and one from Martin Fowler.
While I can generally suggest going to the source for the term, there is something to be said for a term getting overloaded or overused so that it can have little meaning. There are a few folks' blogs that I can say I trust to get some understanding on a subject including Joels and Jeffs, but don't forget that each of us has a brain and we shouldn't be afraid to use it.