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Medical Dictionary: o

Word	Definition
O2	oxygen
OB	obstetrics
ob-	against
OB/GYN	obstetrics & gynecology
obesity	Being too heavy for one's height.
oblique	A slanting direction.
obsessive behavior	Repetitive, compulsive behavior.
obsessive compulsive disorder	An anxiety disorder characterized by recurrent, unwanted obsessions and compulsions.
obstetr/o	midwife
obstetrician	A medical doctor specialized in the management of pregnancy, labor and birth
obstetrics	The branch of medicine concerned with the care of women during pregnancy, parturition, and the puerperium.
obstipation	Severe constipation caused by obstruction in the intestines.
obtund	To blunt or deaden pain.
obturator muscle	Either of the two muscles that cover the outer surface of the anterior wall of the pelvis, responsible for rotating the thighs outward.
OC	oral contraceptive
occipital bone	The curved, shield-shaped bone forming the lower rear part of the skull, enclosing the foramen magnum.
occlusion	The blockage of a blood vessel.
OCD	obsessive-compulsive disorder
ochronosis	The discoloration of body tissues,due to a metabolism disorder.
oct-	eight
ocul/o	eye
ocular absorption	Uptake of substances by tissues of the eye.
ocular hypertension	A condition in which the intraocular pressure is elevated above normal and which may lead to glaucoma.
ocular hypotension	Abnormally low intraocular pressure often related to chronic inflammation.
oculomotor	Pertaining to or affecting eye movements.
odont/o	tooth
odontogenesis	The process of tooth development.
odontoma	A mixed tumor of odontogenic origin,
odyn-	pain
odynophagia	Painful swallowing.
-oid	resembling
ointments	A medicated formulation with an oil base
-ole	small, little
oleo-	oil
olfact/o	smell
olfactory	Relating to the sense of smell.
olfactory bulb	The area of the forebrain where the olfactory nerves terminate.
olfactory nerve	The first cranial nerve. The olfactory nerve conveys the sense of smell.
olig/o	few, scanty
oligodontia	Absence of some teeth.
oligohydramnios	A condition of abnormally low amniotic fluid volume.
oligomenorrhea	Light or infrequent menstrual periods.
oligospermia	A deficiency of spermatozoa in the semen, defined as a sperm count below 20 million per milliliter semen.
oliguria	Decreased urinary output.
om/o	shoulder
-oma	tumor, neoplasm
omentum	A double-layered fold of peritoneum that attaches the stomach to other organs in the abdominal cavity.
omphal/o	umbilicus (navel)
omphalitis	Inflammation of the umbilicus.
onc/o	swelling, tumor
oncocytoma	A rare, benign tumor usually occurring in the parotid glands in older patients.
oncogene	A mutated gene that causes the transformation of normal cells into cancerous cells.
oncolysis	Destruction of a neoplasm.
oncotic	Pertaining to swelling or edema.
ontogeny	The developmental history of an individual from inception to maturity.
onych/o	fingernail, toenail
onychocryptosis	An ingrown toenail.
onycholysis	Loosening or separation of nail plate from the underlying nail bed.
onychomycosis	A fungal infection of the nails.
oophor/o	ovary
oophorectomy	Surgical removal of an ovary or ovaries.
oophoritis	Inflammation of the ovary.
OPD	outpatient department
operculum	A lid or covering.
ophry/o	eyebrow
ophthalm/o	eye
ophthalmia	Severe inflammation of the eye.
ophthalmic	Pertaining to the eye.
ophthalmology	A surgical specialty concerned with the treatment of eye defects and diseases.
ophthalmoplegia	Paralysis of one or more of the ocular muscles.
ophthalmoscopy	An examination of the back part of the eye (fundus), which includes the retina, optic disc, choroid, and blood vessels.
-opia	vision condition
opiate	A narcotic containing opium or its derivatives.
opisth-	behind
opium	The air-dried juice of the unripe seed capsule of the opium poppy.
opposition	Relation of the position of the thumb to the other fingers.
-opsy	process of viewing
opt/o	eye, vision
optic nerve	The second cranial nerve which conveys visual information from the retina to the brain.
optic neuritis	Inflammation of the optic nerve.
optic tract	Nerve fiber originating from the optic chiasm that connects predominantly to the lateral geniculate bodies. it is the continuation of the visual pathway that conveys the visual information originally from the retina to the optic chiasm via the optic nerves.
optometry	The professional practice of primary eye and vision care that includes the measurement of visual refractive power and the correction of visual defects with lenses or glasses.
OR	operating room
or/o	mouth
oral	Pertaining to the mouth.
oral hygiene	The practice of personal hygiene of the mouth. It includes the maintenance of oral cleanliness, tissue tone, and general preservation of oral health.
orbit	Bony cavity that holds the eyeball and its associated tissues and appendages.
orbital myositis	Inflammation of the extraocular muscle of the eye. It is characterized by swelling.
orchid/o	testicles
orchidalgia	Pain in the testicle.
orchidectomy	Surgical removal of one or both testicles.
orchiectomy	The surgical removal of one or both testicles.
orchiopexy	Surgery to move an undescended testicle into the scrotum.
orchitis	Inflammation of a testis.
-orexia	appetite
organ/o	organ
organelles	Specialized intracellular structure present in eukaryotic cells.
organogenesis	Formation of differentiated cells and complicated tissue organization to provide specialized functions.
orgasm	The climax of sexual excitement.
ori-	mouth
ORIF	open reduction internal fixation
oropharynx	The middle portion of the pharynx that lies posterior to the mouth, inferior to the soft palate, and superior to the base of the tongue and epiglottis.
orth/o	straight
orthodontics	The dental specialty dealing with correction of dental abnormalities.
orthopedics	A surgical specialty which treats and corrects injuries, deformities and diseases to the skeletal system and joints.
orthopnea	Dyspnea when lying flat.
orthostatic	Pertaining to a erect posture.
orthotic	A device for correcting an orthopedic problem. Commonly used for the foot.
orthotic devices	A device used to support, align, or correct deformities of movable parts of the body.
osche/o	scrotum
oscill/o	swing
-ose	a carbohydrate
OSHA	Occupational Safety and Health Administration
-osis	abnormal condition
osm/o	sense of smell
osmosis	Tendency of fluids to move from the less concentrated to the more concentrated side of a semipermeable membrane.
oss/e	bone
oss/i	bone
osseous	Composed of or resembling bone.
ossicle	A small bone, especially of the middle ear.
ossification	The formation of bone.
oste/o	bone
osteitis	Inflammation of the bone.
osteoarthritis	A progressive, degenerative joint disease, the most common form of arthritis.
osteoblastoma	A benign, painful, vascular tumor of bone marked by the formation of osteoid tissue, primitive bone and calcified tissue.
osteochondritis	Inflammation of a bone and its overlaying cartilage.
osteochondroma	A cartilage-capped benign tumor that often appears as a stalk on the surface of bone.
osteochondrosis	Any of a group of disorders of the growth ossification centers in children
osteocytes	Mature osteoblasts that have become embedded in the bone matrix.
osteogenesis	The process of bone formation.
osteology	The science that studies the structure and function of bones.
osteolysis	Dissolution of bone.
osteoma	A benign, slow growing tumor composed of bone tissue.
osteomalacia	An interruption of the mineralization of organic bone matrix leading to bone softening, bone pain, and weakness. It is the adult form of rickets.
osteonecrosis	Death of a bone or part of a bone.
osteophyte	Bony projection usually found around joints and often seen in arthritis.
osteoporosis	Reduction of bone mass without alteration in the composition of bone, leading to fractures.
osteosarcoma	A sarcoma originating in bone-forming cells, affecting the ends of long bones.
osteosclerosis	An abnormal hardening or increased density of bone tissue.
osteotomy	Cutting of a bone.
ostomy	Surgery to create an artificial opening (stoma) into the urinary or gastrointestinal canal.
OT	occupational therapy
ot/o	ear, hearing
otalgia	Ear ache.
OTC	over-the-counter
otitis	Inflammation of the ear, which may be marked by pain, fever, hearing disorders and vertigo.
otitis media	An ear infection of the middle ear, the area just behind the eardrum.
otolaryngology	A surgical specialty concerned with the study and treatment of disorders of the ear, nose, and throat.
otology	The study of diseases of the ear.
otomycosis	A fungal infection of the external auditory canal.
otopyorrhea	Discharge of pus from ear.
otorrhea	Ear discharge.
otosclerosis	A disease of the bones of the middle and inner ear.
otoscope	An instrument designed to inspect the ear.
-ous	pertaining to
ov/o	egg, ovum
ovari/o	ovary
ovarian	Pertaining to the ovary.
ovarian cysts	General term for cysts and cystic diseases of the ovary.
ovarian neoplasms	Tumors or cancer of the ovary. These neoplasms can be benign or malignant.
ovary	Either of the sex glands in females. They produce ova and hormones.
ovulation	The discharge of an ovum from a rupturing follicle in the ovary.
ovum	A mature haploid female germ cell extruded from the ovary at ovulation.
ox/i	oxygen
ox/o	oxygen
oxa-	oxygen
oximetry	The determination of oxygen-hemoglobin saturation of blood.
OXT	oxytocin
oxy-	sharp, oxygen
oxygen	An element with atomic symbol O, atomic number 8, and atomic weight [15.99903; 15.99977]. It is the most abundant element on earth and essential for respiration.
oxytocin	A hormone secreted by the pituitary gland. It simulates contraction during labor and the production of milk.
oz	ounce
ozone	An unstable, poisonous allotrope of oxygen.