[Asraelite]

Does anyone know why they chose "ronna" instead of "renna"? It should be r + ennea (Greek for nine), so where does the "o" come from?

Every prefix up until now has been consistent about the first vowel mirroring the Greek word:

  tetra -> tera
  penta -> peta
  hex -> exa
  hepta -> zetta
  okto -> yotta