'Jargon' is a contemptuous term for the specialist language of a professional group. We are often told to avoid it in writing and speech, and yet it does have its uses: no one expects brain surgeons to have the same technical vocabulary as electronic engineers. What some might call 'jargon' is, in those circumstances, economical and precise: it's the right language to use.
The snag comes when people use that vocabulary with outsiders, to mystify and bamboozle, or to glamorise concepts that can easily be explained in plain English. The word 'jargon' was originally French, but it has been used in English since the 14th century to mean unintelligible or meaningless talk, nonsense, or gibberish. It has also been used as a way of disparaging other people's languages. At first, it meant something incomprehensible to the whole human race: the twittering and tweeting of birds. Of course, we are all tweeting now, if you will excuse the jargon.