Criminal law, traffic matters, DUI, assault, theft, fraud
It is hard to explain without giving an example. However as I have no idea what your case is about the example may be way out of the area.
But for this exercise lets assume yours is an industrial case and revolves around an instruction you received. The dictionary description of the duties involved in relation to that instruction may be completely different to the meaning that applies in your workplace. That is what I mean by common usage. Any court hearing the case would apply the meaning that applies and that is in common use at your workplace.