The term 'MOST FESTIVE' can be solved by the word 'GAYEST', which is a six-letter word. The term 'GAYEST' is often used to describe something that is very cheerful and lively, usually in reference to a celebration or holiday. It is also used to describe someone who is very happy and joyful. Therefore, the term 'MOST FESTIVE' can be used to describe something that is extremely cheerful and lively, and is likely to be associated with a festive event.