The "Jargon File" is the de facto
official dictionary of hacker terms, we're not talking about just some jargon people in that group tend to use. Yes, hacker can be used for other things---it's also a golf term as your dictionary states---but the hacker sub-culture has its own dictionary called the Jargon File that defines it in the way that it was originally meant when applied to programmers and computer science.
Also, people should stop using dictionaries as the go-to source for their argument-from-authority fallacies. They're no more official than any other source. English, unlike some languages (I believe French and Norwegian do), has no official regulatory committee, so there's no "official" English dictionary, hence why there are so many competing ones. Dictionary authors have the same level of authority as anyone else: that is, none at all. The only difference is that they do research. But anyone can research the etymology and the history of the various meanings of words; it doesn't require much expertise, just a lot of effort poring through old tomes. It's not like physics or medicine where you need special skills to interpret what you're seeing; the only skill you need is the ability to read (specifically, to read middle English; although Latin, Greek, German, Norse, French, old English, etc. will all help too).
Evidence that dictionaries are useless:
1. In a literal manner or sense; exactly: "the driver took it literally when asked to go straight over the traffic circle".
2. Used to acknowledge that something is not literally true but is used for emphasis or to express strong feeling.
See how they pander to the idiots that use words incorrectly? And this is not just some per se/per say confusion; this is literally (and I do mean literally) giving the words the opposite meaning to the meaning they currently have. I know this isn't new, but that doesn't make it right (otherwise that's another fallacy, called argument-from-history). Words mean what they mean, not what people just happen to be using them to mean. And before someone points out that I'm probably using several words differently to their original meaning: that is a product of the mistakes of others---namely, those who allowed the meanings of the words to change, as well as the people who taught me the wrong meanings---not of myself. English should be regulated; the meanings of words should be fixed to what they are now, and not allowed to change just because people like Alanis Morissette can't grasp the concept of irony.