Wu Zetian's real name (birth name) has been lost and there is no historical record. Wu Mei was made emperor by Emperor Taizong, and Zetian was called emperor because he ascended the throne in Zetianmen. Wu Zhao was the name she gave herself when she became emperor.
There are two interpretations of the name Wu Zhao. It's not clear which one is true. A solution means that the sun and the moon are in the sky, shining mountains and rivers, and ensuring the inheritance of all things in the Tang Dynasty; The second plan is that when she became a monk, her legal name was Kongming, and later she called Kongming a coffin. This word was invented by Wu Zetian.