Septennial refers to something that occurs every seven years. So, synonyms for the term "more septennial" would be phrases and words that convey the same meaning or something that happens at an interval of seven years or so. Use words like "heptennial" or "septenary" to describe something that takes place every seven years. "Setenniel" is another synonym that can be used to refer to events that happen seven years apart. Alternative words like "seven-year," "septennial" or "heptennial" can also fit the bill when describing an event or occurrence that happens every seven years without fail. These synonyms can make writing more expressive and vivid, presenting a more vivid picture to the reader.