Ninkharsag is a Sumerian word that refers to the goddess of the mountains. As it is a proper noun, there are no synonyms for this word. However, there are other names used to describe goddesses of the mountains in different cultures and mythologies. For instance, in Greek mythology, the mountain goddess is known as Gaia. In Hindu mythology, the goddess of the mountains is Parvati. Similarly, in Norse mythology, the mountain goddess is called Skaði. Although there is no direct synonym for Ninkharsag, the concept of a mountain goddess is universal and can be found in numerous religions and cultures worldwide.