There are many synonyms for the phrase "on terra firma," which refers to being on solid ground. Some common alternatives include "on solid ground," "on dry land," "on the ground," "on foot," "on the surface," and "on land." Other phrases that convey a similar meaning include "on stable ground," "on safe ground," and "on level ground." These phrases are often used metaphorically to describe feeling secure or confident in one's position. Regardless of the specific wording, the idea of "being on solid ground" is a universal concept that resonates with people across cultures and languages.