 The names Mṛgaśira (मृगशिर) and Mārgaśīrṣa/Mṛgaśīrṣa (मार्गशीर्ष) are sometimes used interchangeably.Grammatically, Mārgaśīrṣa (मार्गशीर्ष) means "of Mṛgaśira" or "related to Mṛgaśira".Thus Mṛgaśira (मृगशिर) is the correct name of the star, while Mārgaśīrṣa (मार्गशीर्ष) is the name of the month related to Mṛgaśira, i.e., the month in which moon will be in conjuncture with the Mṛgaśira nakṣatra.