In Hindu astrology, Mangal Dosh is an astrological combination that occurs if Mars (Mangal) is in the 1st, 2nd (Considered by South Indian Astrologers), 4th, 7th, 8th, or 12th house of the ascendant chart. A person born in the presence of this condition is termed a manglik.
Sridar Sairam Demystifying the secrets of astrology & gemstones