NOUN (3)

1. a married woman (usually middle-aged with children) who is staid and dignified;

2. a wardress in a prison;

3. a woman in charge of nursing in a medical institution;

The Collaborative International Dictionary of English v.0.48:

Matron \Ma"tron\, n. [F. matrone, L. matrona, fr. mater mother.
   See Mother.]
   1. A wife or a widow, especially, one who has borne children;
      a woman of staid or motherly manners.
      [1913 Webster]

            Your wives, your daughters,
            Your matrons, and your maids.         --Shak.
      [1913 Webster]

            Grave from her cradle, insomuch that she was a
            matron before she was a mother.       --Fuller.
      [1913 Webster]

   2. A housekeeper; esp., a woman who manages the domestic
      economy of a public instution; a head nurse in a hospital;
      as, the matron of a school or hospital.
      [1913 Webster]

   Jury of matrons (Law), a jury of experienced women called
      to determine the question of pregnancy when set up in bar
      of execution, and for other cognate purposes.
      [1913 Webster]

WordNet (r) 3.0 (2006):

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