Some sources suggest Theria comes from the girl's name Eleutheria, meaning "free" in Greek, but other sources suggest it comes from Theresa, from the Greek word theros, meaning "late summer," and that people with this name may have come from the island of Therasia. It could also be the feminine form of Theron, meaning "hunter." The most famous bearer of that name is Mother Theresa, although there were two saints with the name.
There was also an ancient island called Thera, on which there was a Bronze Age volcanic eruption, said to have caused the end of the Minoan Civilization (from which we get the Atlantis myths).
There were no baby girls born in 2010 with the name Theria. Theria is pronounced THER-ee-ya or TAYR-ee-ah if you like the Theresa root. Enjoy this rare, beautiful name.