Dictionary.com
Thesaurus.com

ennea-

American  
  1. a combining form meaning “nine,” used in the formation of compound words.

    enneahedron.


Usage

What does ennea- mean? Ennea- is a combining form used like a prefix meaning “nine.” It is used in some scientific and other technical terms. Ennea- comes from the Greek ennéa, meaning “nine.” The Latin counterpart is nōnus, meaning “ninth” and source of the combining form nona-, which you can learn more about in our Words That Use articles for that form.

Etymology

Origin of ennea-

< Greek, combining form of ennéa nine