matron

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A married woman or a widow, especially a mother of dignity, mature age, and established social position.
2. n. A woman who acts as a supervisor or monitor in a public institution, such as a school, hospital, or prison.

Century Dictionary and Cyclopedia

1. n. A married woman, especially an elderly married woman, or a woman old enough to be the mother of a family, whether actually so or not; a woman possessing the gravity suitable to a mother.
2. n. In a special sense, a head nurse in a hospital; the female head or superintendent of any institution.

Wiktionary

1. n. A mature woman; a wife or a widow, especially, one who has borne children; a woman of staid or motherly manners.
2. n. A housekeeper; especially, a woman who manages the domestic economy of a public institution; a head nurse in a hospital; as, the matron of a school or hospital.

GNU Webster's 1913

1. n. A wife or a widow, especially, one who has borne children; a woman of staid or motherly manners.
2. n. A housekeeper; esp., a woman who manages the domestic economy of a public instution; a head nurse in a hospital.

WordNet 3.0

1. n. a wardress in a prison
2. n. a woman in charge of nursing in a medical institution
3. n. a married woman (usually middle-aged with children) who is staid and dignified