Ennea- is a Greek prefix that means nine. There are several synonyms for this prefix, including nona-, novem-, and ix-. These prefixes are commonly used in different contexts, such as in mathematics and biology. For example, the nonagon is a nine-sided polygon, while the Novemdecillion is a number representing 1 with 60 zeros. In biology, the ixodidae family includes ticks, which have nine pairs of legs. In astronomy, Novem means the ninth planet in the solar system. These synonyms can be useful when trying to communicate effectively and efficiently in different fields that use the same concept of "nine".