- Marriage--Moral and ethical aspects1
- Martino, Odino S., active 15th century1
- Mary, Blessed Virgin, Saint, in the liturgy1
- Masorah1
- Mathematics1
- Mathematics, Greek1
- Maurice, Saint, -approximately 2871
- Maximus, of Turin, Saint, active 4th century-5th century1
- Medicine, Greek and Roman--Manuscripts1
- Medicine, Magic, mystic, and spagiric1
- Mediterranean Sea1
- Merlin (Legendary character)1
- Metaphysics1
- Mezuzah1
- Middle East1
- Middle East--Palestine1
- Military history, Medieval1
- Mills and mill-work1
- Miniature books1
- Minors (Canon law)1