Octonary is a word that describes something that consists of or pertains to eight. If you're looking for synonyms with the same meaning, you could use words like "octet," "eightfold," or "octave." You might also consider using phrases like "in groups of eight" or "eight-part." Additionally, there are several words that describe groups of eight that could be used synonymously with octonary, such as "octad," "octet," "octoplet," and "octuple." Whether you're writing about music, math, or anything else that involves the number eight, these synonyms for octonary will help you to express yourself with precision and clarity.