From Xevious Wiki :

The Xevi language (ゼビ語) is a language in the Xevious series created by Masanobu Endō to give more realism to the setting. However, it is rarely used in the video games from the series, only being seen in the ending of the MSX2 version of Xevious: Fardraut Saga. It is also described as "Ancient Pan Galactic Official Language (古代汎銀河公用語 【こだいはんぎんがこうようご】."

The name of the main ship and the enemies in the series are based on the Xevi language. For example, "Solvalou" means "sunbird" and "Garu" means "huge" in the Xevi language.