People do use different terminologies.But unfortunately they are either centered in certain area of the world or with in few organizations who migrate and carry those sticky things with them.
Core area is a word which denotes the PROCESSING AREA WHERE ALL EQUIPEMNTS ARE HOUSED UNDER CLASS 100 AREA.
In other words it also means Sterile Filling zone or Filling area.
This is an area where utmost sterility assurance is needed.
Please follow phramaceutical terminology always.Never learn these catchy words.
You may not have a perfect grammer like a native English speaker, but Pharmaceutical Terminology is universal.