a characteristic language of a particular group
The specialised or technical language of a trade, profession, or similar group
has also come to mean inflated, vague, meaningless language of any kind. It is characterized by wordiness, abstractions galore, pretentious diction, and needlessly complicated word order.
It is generally agreed that using jargon in a piece of writing is bad writing. However from a teaching/induction point of view, we like our learners to become familar with the jargons of the trade/profession they are induced into.
What we should object, in writing, is the "wordiness, abstractions galore, pretentious diction, and needlessly complicated word order". When we are writing a piece for audience outside the community, we should try to avoid jargon - to a certain degree.
Some jargons refer to procedures (CPR in first aid for example stands for Cardio-Pulmonary Resuscitation, which when fully spelt out still means nothing to those without first aid training!), other refer to a theory (Newton's law of motion). Jargons, in fact, are short-hands.
Jargon is a necessary part of an efficient communication - provided they are part of a communication to the correct audience.