- Nasology : The study of nose
- Nautics : The art of navigation
- Nematology : The study of nematodes
- Neonatology : The study of newborn babies
- Nephology : The study of clouds
- Nephrology : The study of kidneys
- Neurobiology : The study of anatomy of nervous system
- Neurology : The study of nervous system
- Neuropharmacology : The study of action of drugs on the nervous system
- Neurophysiology : The study of physiology of the nervous system
- Neuropscychology : The study of relation between brain and human behaviour
- Neurypnology : The study of hypnotism
- Nidology : The study of nests
- Noology : The science of intuition
- Nosology : The study of diseases
- Nostology : The study of senility
- Numerology : The study of numbers
- Obstetrics : The study of midwifery
- Obstetrics : The study of newborn babies
- Oceanography : The study of oceans
- Odontology : The study of teeth
- Olfactology : The study of the sense of smell
- Ombrology : The study of rain
- Oncology : The study of tumours
- Ontology : The science of pure being; the nature of things
- Oology : The study of eggs
- Ophiology : The study of snakes
- Ophthalmology : The study of eyes diseases
- Optics : The study of light
- Optology : The study of sight
- Optometry : The science of examining the eyes
- Ornithology : The study of birds
- Orology : The study of mountains
- Osmology : The study of smells and olfactory processes
- Osteology : The study of bones
- Otology : The study of the ear
- Otorhinolaringology : The study of ear, nose and throat
- Paediatrics : The study of children’s diseases
- Palaeoanthropology : The study of early humans
- Palaeobiology : The study of fossil plants and animals
- Palaeobotany : The study of ancient plants
- Palaeoclimatology : The study of ancient climate
- Palaeolimnology : The study of ancient lakes or fish
- Palaeontology : The study of fossils
- Palaeo-osteology : The study of pre-historic bones
- Palaeopedology : The study of early soils
- Palynology : The study of live & fossil spores & pollen
- Pamology : The study of fruit-growing
- Parapsychology : The study of unexplained mental phenomenon
- Parasitology : The study of parasites
- Pathology : The study of disease
- Pedology : The study of soils
- Penology : The study of crime and punishment
- Periodontics : The study of gums
- Pestology : The science of pests
- Petrology : The study of rocks
- Pharmacology : The study of drugs
- Pharyngology : The study of throat
- Phenology : The study of organisms as affected by climate
- Phenomenology : The study of phenomena
- Phoniatrics : The study and correction of speech defects
- Phonology : The study of speech sounds
- Photobiology : The study of of effects of light on organism
- Phrenology : The study of bumps on the head
- Phycology : The study of algae and seaweeds
- Physics : The study of properties of matter and energy
- Physiology : The study of processes of life
- Phytology : The study of plants
- Piscatology : The study of fishes
- Planetology : The study of planets
- Pneumatics : The study of mechanics of gases
- Podiatry : The study and treatment of disorders of the foot
- Posology : The science of quantity or dosage
- Potamology : The study of rivers
- Primatology : The study of primates
- Proctology : The study of rectum
- Psephology : The study of election results and voting trends
- Pseudoptics : The study of optical illusions
- Psychobiology : The study of biology of the mind
- Psychogenetics : The study of internal or mental states
- Psychogenetics : The study of optical illusions
- Psychognosy : The study of mentality, personality of the character
- Psychology : The study of mind
- Psychopathology : The study of mental illness
- Psychophysics : The study of link between mental and physical process
- Pteridology : The study of ferns
- Pterylology : The study of distribution of feathers on birds
- Pyretology : The study of fevers
