The word "terras" is a military term that refers to an embankment or fortified earthwork used for protection and defense. Some synonyms that can be used instead of "terras" include rampart, parapet, fortification, bulwark, embankment, earthwork, barricade, and redoubt. These words all have similar meanings and can be used interchangeably depending on the desired effect or context of the sentence. For example, one might use "rampart" to describe a long and continuous fortification, while "barricade" could be used to describe a hastily constructed barrier for protection. Regardless of the chosen synonym, all these words convey the sense of strength, security, and permanence that comes with well-built fortifications.