The term 'regarding that matter' can be summed up with the word 'therein', which is a seven-letter word. It is an adverb that means 'in or into that place, thing, or matter'. It is often used to refer to something that has already been mentioned or discussed. It can also be used to refer to a specific part of a document or conversation. In this context, it implies that the matter being discussed is related to something that has already been mentioned.