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Medical Dictionary - Letter: o



TermDefinitionPronunciation
O2oxygen
OBobstetrics
ob-against
OB/GYNobstetrics & gynecology
obesityBeing too heavy for one's height.ō-bē'si-tē
obliqueA slanting direction.o-blēk´
obsessive behaviorRepetitive, compulsive behavior.
obsessive compulsive disorderAn anxiety disorder characterized by recurrent, unwanted obsessions and compulsions.
obstetr/omidwife
obstetricianA medical doctor specialized in the management of pregnancy, labor and birthob″stĕ-trĭ´shun
obstetricsThe branch of medicine concerned with the care of women during pregnancy, parturition, and the puerperium.
obstipationSevere constipation caused by obstruction in the intestines.
obtundTo blunt or deaden pain.
obturator muscleEither of the two muscles that cover the outer surface of the anterior wall of the pelvis, responsible for rotating the thighs outward.
OCoral contraceptive
occipital boneThe curved, shield-shaped bone forming the lower rear part of the skull, enclosing the foramen magnum.
occlusionThe blockage of a blood vessel.ŏ-kloo´zhun
OCDobsessive-compulsive disorder
ochronosisThe discoloration of body tissues,due to a metabolism disorder.
oct-eight
ocul/oeye
ocular absorptionUptake of substances by tissues of the eye.
ocular hypertensionA condition in which the intraocular pressure is elevated above normal and which may lead to glaucoma.
ocular hypotensionAbnormally low intraocular pressure often related to chronic inflammation.
oculomotorPertaining to or affecting eye movements.
odont/otooth
odontogenesisThe process of tooth development.
odontomaA mixed tumor of odontogenic origin,
odyn-pain
odynophagiaPainful swallowing.
-oidresembling
ointmentsA medicated formulation with an oil base
-olesmall, little
oleo-oil
olfact/osmell
olfactoryRelating to the sense of smell.
olfactory bulbThe area of the forebrain where the olfactory nerves terminate.
olfactory nerveThe first cranial nerve. The olfactory nerve conveys the sense of smell.
olig/ofew, scanty
oligodontiaAbsence of some teeth.
oligohydramniosA condition of abnormally low amniotic fluid volume.
oligomenorrheaLight or infrequent menstrual periods. ol″ĭ-go-men″o-re´ah
oligospermiaA deficiency of spermatozoa in the semen, defined as a sperm count below 20 million per milliliter semen.
oliguriaDecreased urinary output. ol″ĭ-gu´re-ah
om/oshoulder
-omatumor, neoplasm
omentumA double-layered fold of peritoneum that attaches the stomach to other organs in the abdominal cavity.
omphal/oumbilicus (navel)
omphalitisInflammation of the umbilicus.
onc/oswelling, tumor
oncocytomaA rare, benign tumor usually occurring in the parotid glands in older patients.
oncogeneA mutated gene that causes the transformation of normal cells into cancerous cells.
oncolysisDestruction of a neoplasm.
oncoticPertaining to swelling or edema.
ontogenyThe developmental history of an individual from inception to maturity.
onych/ofingernail, toenail
onychocryptosisAn ingrown toenail.on″ĭ-ko-krip-to´sis
onycholysisLoosening or separation of nail plate from the underlying nail bed.
onychomycosisA fungal infection of the nails.on″ĭ-ko-mi-ko´sis
oophor/oovary
oophorectomySurgical removal of an ovary or ovaries.o″of-o-rek´to-me
oophoritisInflammation of the ovary.
OPDoutpatient department
operculumA lid or covering.
ophry/oeyebrow
ophthalm/oeye
ophthalmiaSevere inflammation of the eye.
ophthalmicPertaining to the eye.
ophthalmologyA surgical specialty concerned with the treatment of eye defects and diseases.
ophthalmoplegiaParalysis of one or more of the ocular muscles.
ophthalmoscopyAn examination of the back part of the eye (fundus), which includes the retina, optic disc, choroid, and blood vessels.of″thal-mos´kah-pe
-opiavision condition
opiateA narcotic containing opium or its derivatives.
opisth-behind
opiumThe air-dried juice of the unripe seed capsule of the opium poppy.
oppositionRelation of the position of the thumb to the other fingers.
-opsyprocess of viewing
opt/oeye, vision
optic nerveThe second cranial nerve which conveys visual information from the retina to the brain.
optic neuritisInflammation of the optic nerve.
optic tractNerve 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.
optometryThe 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.
ORoperating room
or/omouth
oralPertaining to the mouth.
oral hygieneThe practice of personal hygiene of the mouth. It includes the maintenance of oral cleanliness, tissue tone, and general preservation of oral health.
orbitBony cavity that holds the eyeball and its associated tissues and appendages.
orbital myositisInflammation of the extraocular muscle of the eye. It is characterized by swelling.
orchid/otesticles
orchidalgiaPain in the testicle.
orchidectomySurgical removal of one or both testicles.or″ke-ek´to-me
orchiectomyThe surgical removal of one or both testicles.
orchiopexySurgery to move an undescended testicle into the scrotum.or´ke-o-pek″se
orchitisInflammation of a testis.
-orexiaappetite
organ/oorgan
organellesSpecialized intracellular structure present in eukaryotic cells.
organogenesisFormation of differentiated cells and complicated tissue organization to provide specialized functions.
orgasmThe climax of sexual excitement.
ori-mouth
ORIFopen reduction internal fixation
oropharynxThe 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/ostraight
orthodonticsThe dental specialty dealing with correction of dental abnormalities.
orthopedicsA surgical specialty which treats and corrects injuries, deformities and diseases to the skeletal system and joints.
orthopneaDyspnea when lying flat.
orthostaticPertaining to a erect posture.
orthoticA device for correcting an orthopedic problem. Commonly used for the foot.or-thot´ik
orthotic devicesA device used to support, align, or correct deformities of movable parts of the body.
osche/oscrotum
oscill/oswing
-osea carbohydrate
OSHAOccupational Safety and Health Administration
-osisabnormal condition
osm/osense of smell
osmosisTendency of fluids to move from the less concentrated to the more concentrated side of a semipermeable membrane.
oss/ebone
oss/ibone
osseousComposed of or resembling bone.
ossicleA small bone, especially of the middle ear.
ossificationThe formation of bone.
oste/obone
osteitisInflammation of the bone. os″te-i´tis
osteoarthritisA progressive, degenerative joint disease, the most common form of arthritis.os″te-o-ahr-thri´tis
osteoblastomaA benign, painful, vascular tumor of bone marked by the formation of osteoid tissue, primitive bone and calcified tissue.
osteochondritisInflammation of a bone and its overlaying cartilage.
osteochondromaA cartilage-capped benign tumor that often appears as a stalk on the surface of bone.os″te-o-kon-dro´mah
osteochondrosisAny of a group of disorders of the growth ossification centers in children
osteocytesMature osteoblasts that have become embedded in the bone matrix.
osteogenesisThe process of bone formation.
osteologyThe science that studies the structure and function of bones.
osteolysisDissolution of bone.
osteomaA benign, slow growing tumor composed of bone tissue.
osteomalaciaAn interruption of the mineralization of organic bone matrix leading to bone softening, bone pain, and weakness. It is the adult form of rickets.os″te-o-mah-la´shah
osteonecrosisDeath of a bone or part of a bone.os″te-o-nĕ-kro´sis
osteophyteBony projection usually found around joints and often seen in arthritis.
osteoporosisReduction of bone mass without alteration in the composition of bone, leading to fractures. os″te-o-po-ro´sis
osteosarcomaA sarcoma originating in bone-forming cells, affecting the ends of long bones. os″te-o-sahr-ko´mah
osteosclerosisAn abnormal hardening or increased density of bone tissue.
osteotomyCutting of a bone.
ostomySurgery to create an artificial opening (stoma) into the urinary or gastrointestinal canal.
OToccupational therapy
ot/oear, hearing
otalgiaEar ache.o-tal´jah
OTCover-the-counter
otitisInflammation of the ear, which may be marked by pain, fever, hearing disorders and vertigo.
otitis mediaAn ear infection of the middle ear, the area just behind the eardrum.o-ti´tis
otolaryngologyA surgical specialty concerned with the study and treatment of disorders of the ear, nose, and throat.
otologyThe study of diseases of the ear.
otomycosisA fungal infection of the external auditory canal.o″to-mi-ko´sis
otopyorrheaDischarge of pus from ear.o″to-pi″o-re´ah
otorrheaEar discharge.o″to-re´ah
otosclerosisA disease of the bones of the middle and inner ear.o″to-sklĕ-ro´sis
otoscopeAn instrument designed to inspect the ear.
-ouspertaining to
ov/oegg, ovum
ovari/oovary
ovarianPertaining to the ovary.
ovarian cystsGeneral term for cysts and cystic diseases of the ovary.
ovarian neoplasmsTumors or cancer of the ovary. These neoplasms can be benign or malignant.
ovaryEither of the sex glands in females. They produce ova and hormones.
ovulationThe discharge of an ovum from a rupturing follicle in the ovary.
ovumA mature haploid female germ cell extruded from the ovary at ovulation.
ox/ioxygen
ox/ooxygen
oxa-oxygen
oximetryThe determination of oxygen-hemoglobin saturation of blood.
OXToxytocin
oxy-sharp, oxygen
oxygenAn 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.
oxytocinA hormone secreted by the pituitary gland. It simulates contraction during labor and the production of milk. ok″se-to´sin
ozounce
ozoneAn unstable, poisonous allotrope of oxygen.