- Mandrake
- Maneb
- Manganese
- Manganese deficiency
- Manganese superoxide dismutase
- Manganism
- Mange
- Mangoes
- Mangostin
- Manhattan plot
- Mania
- Manipulation
- Manipulation check
- Manipulation under anesthesia
- Manipulative therapy
- Mannan
- Mannan-binding lectin
- Mannans
- Manner of articulation
- Mannich bases
- Manning criteria
- Mannitol
- Mannitol dehydrogenase
- Mannitol salt agar
- Mannosamine
- Mannose
- Mannose 6-phosphate
- Mannose receptor
- Mannose-6-phosphate
- Mannose-binding lectin
- Mannosidase
- Mannosidosis
- Mannosyltransferase
- Manometry
- Mansonella
- Mansonella ozzardi
- Mansonella perstans
- Mantel test
- Mantle
- Mantle zone
- Mantoux test
- Manual Ability Classification System
- Manual communication
- Manual handling of loads
- Manual lymphatic drainage
- Manual small incision cataract surgery
- Manual therapy
- Manubrium
- Map kinase phosphatase
- Mapatumumab
- Maple syrup urine disease
- Maprotiline
- Maraviroc
- Marble burying
- Marburg virus
- Marburg virus disease
- Marburgvirus
- Marchiafava-Bignami disease
- Marek's disease
- Maresin
- Marfan syndrome
- Marfanoid
- Margaric acid
- Margatoxin
- Margin of error
- Marginal Structural Model
- Marginal distribution
- Marginal mandibular branch
- Marginal sinus
- Marginal zone
- Marginal zone B cells
- Marginal zone B-cell lymphoma
- Marginal zone lymphoma
- Marginalization
- Maribavir
- Marijuana abuse
- Marimastat
- Marine pollution
- Marine snow
- Marinobacter
- Marionette lines
- Marjolin's ulcer
- Marjoram
- Marker chromosome
- Marker gene
- Marker-assisted selection
- Marketing authorisation
- Marlex
- Marlowe-Crowne Social Desirability Scale
- Marmesin
- Maroteaux-Lamy syndrome
- Marrow adipose tissue
- Marsh gas
- Marshall syndrome
- Marsupialization
- Martin-Gruber Anastomosis
- MasSpec Pen
- Masked depression
- Masked hypertension
- Masking
- Masking agent
- Maslinic acid
- Maslow's hierarchy of needs
- Masochism
- Maspin
- Mass attenuation coefficient
- Mass balance
- Mass casualty incidents
- Mass communication
- Mass concentration
- Mass cytometry
- Mass density
- Mass diffusivity
- Mass hysteria
- Mass spectrometer
- Mass spectrometry
- Mass spectroscopy
- Mass spectrum
- Mass vaccination
- Massage therapy
- Masseter muscle
- Massive perivillous fibrin deposition
- Masson's trichrome stain
- Mast cell
- Mast cell activation syndrome
- Mast cell leukemia
- Mast cell sarcoma
- Mast cell stabilizers
- Mast cell tumors
- Mast-cell sarcoma
- Mastadenovirus
- Mastalgia
- Mastectomy
- Mastic
- Mastication
- Mastitis
- Mastocytoma
- Mastocytosis
- Mastoid
- Mastoid antrum
- Mastoid process
- Mastoidectomy
- Mastoiditis
- Mastoparan
- Mastopexy
- Mastrevirus
- Matairesinol
- Matchbox sign
- Matching
- Matching law