The antonyms for the word "more extraterrestrial" would be related to the concept of "earthly" or "terrestrial." Words like "mundane," "ordinary," "typical," "commonplace," and "routine" would all be antonyms. These words describe things that are ordinary or are commonly found on Earth. The opposite of extraterrestrial can also refer to things found only on Earth, such as "terrestrial," "earthbound," "planetary," or "geocentric." Thus, if something is described as less extraterrestrial than something else, it means that it is more relatable and connected to life on Earth.