Definition - What does Mitra mean?
Mitra is a Sanskrit word which means "friend." It is a combination of the root words, mi, which means "destruction," and tra, meaning "protective force." The term is best explained as a friend who protects you from harm, guides your through the right path and brings you happiness.
Mitra is also the name of Varuna's twin and one of the 12 sons of Aditi, who is considered the mother of gods, according to the "Rig Veda."
Yogapedia explains Mitra
The 12 sons of Aditi are Mitra, Varuna, Aryaman, Daksa (also Daksha or Dhata), Bhaga, Ansha, Tvashtr (Tvashta), Savitr, Pusan (Pusha), Sakra, Vivasvat (Vivasvan) and Visnu (Vishnu). The 12 sons are also referred to as the 12 spokes of the sun's wheel, which represent the 12 months of the year.
Mitra is always mentioned with his twin Varuna. It is said that Mitra presides over the day while Varuna the night. Mitra is considered to be the god of the sun (or light) and Varuna the god of the moon.
Mitra is the master of knowledge. He is sleepless as he guards creation. He is the light that dispels darkness and promotes harmony, abundance, happiness and wisdom.