- Manuscripts, Yiddish1
- Marie de Médicis, Queen, consort of Henry IV, King of France, 1573-16421
- Maritime law1
- Martellini, Vincenzio1
- Mary, Blessed Virgin, Saint1
- Materia medica1
- Mathematics1
- Medici, Alamanno de'1
- Medici, Bernardo d'Alamanno de'1
- Medici, Carlo de'1
- Medici, Francesca de'1
- Medici, Giuliano de', 1453-14781
- Medici, Niccolò de'1
- Medici, Ottavia Altoviti1
- Medici, Piero di Lorenzo de', 1472-15031
- Medicine1
- Medicine--Study and teaching1
- Merchants1
- Messiah--Judaism1
- Metaphysics1