* Matriarch: A female head of a family or tribe
* Matrilineal: Relating to or based on descent through the female line
* Matrimonial: Relating to marriage
* Matrimony: Marriage
* Matrix: The material within which something develops; the surrounding environment or substance in which something originates, develops, or is contained
* Matriculate: To enroll in a college or university
* Matricide: The act of killing one's mother
* Metropolis: A large city, especially the capital of a country or region
* Matrilocal: Relating to a society in which a married couple lives with or near the wife's parents
* Matriarchy: A system of society or government ruled by women
Note: While "metropolis" also uses the "matri" root, it's more a coincidence than a direct connection to the meaning of "mother."