Gillregion is spelled with two separate parts: "gill" and "region". The word "gill" is spelled with the phonetic transcription /ɡɪl/, which represents the sounds "gih" and "l". The word "region" is spelled with the phonetic transcription /ˈriːdʒən/, which represents the sounds "ree", "juh", and "n". Therefore, the spelling of Gillregion represents two distinct words merged into one, and the correct pronunciation would be /ɡɪlˈriːdʒən/.