By the year 2050 at the very latest not a single human being will be alive who could understand the conversation we are having now. This article is written in Legal English. It's the language of the street. It is a dynamic, loosely defined language, and it can vary considerably from one geographical area to the next. It abounds with special and paradoxical interpretations.
Foreigners always have great difficulty dealing with the various idioms.
Formal English Precise communications require a more formal structure. Formal English is taught in the schools, and it is the language of choice when strangers meet to execute common transactions. It is a stable language that typically requires multi-decades or centuries to evolve its meanings. Unless otherwise specified, English dictionaries cast all words in Formal English, with the more common usage placed at the beginning of the definition. Dictionaries often will show slang or legal meanings as well.