Copy of `Dorland's Medical Dictionary`

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Dorland's Medical Dictionary Category: Health and Medicine > Medical Dictionary Date & country: 31/12/2010, USA Words: 39128

overbite
(o´vәr-bīt″) extension of incisal ridges of the upper anterior teeth below the incisal ridges of the corresponding lower teeth when the jaws are closed normally.

overcoat
(o´ver-kōt) abrasion layer.

overcompensation
(o″vәr-kom″pәn-sa´shәn) conscious or unconscious exaggerated correction for a real or imagined physical or psychological deficiency.

overdenture
(o″vәr-den´chәr) a complete denture supported both by mucosa and by a few remaining natural teeth that have been altered, as by insertion of a long or short coping, to permit the denture to fit over them.

overdosage
(o″vәr-do´sәj) administration of an overdose. the condition resulting from this.

overdose
(o´vәr-dōs″) an excessive dose. to administer an excessive dose.

overflow incontinence
urinary incontinence due to pressure of retained urine in the bladder after the bladder has contracted to its limits; there may be a variety of symptoms, including frequent or constant dribbling or symptoms similar to those of stress or urge incontinence.

overflow proteinuria
that due to hemoglobin, myoglobin, or immunoglobulin loss into the urine due to excessive amounts in the bloodstream, such as in multiple myeloma; it is not usually associated with glomerular or tubular disease.

overhydration
(o″vәr-hi-dra´shәn) hyperhydration.

overjet
(o´vәr-jet″) extension of the incisal or buccal cusp ridges of the upper teeth horizontally (labially or buccally) beyond the ridges of the teeth in the lower jaw when the jaws are closed normally.

overlap syndrome
any of a group of connective tissue disorders that either combine scleroderma with polymyositis or systemic lupus erythematosus or combine systemic lupus erythematosus with rheumatoid arthritis or polymyositis. Cf. mixed connective tissue disease.

overlay denture
a complete denture supported both by soft tissue (mucosa) and by a few remaining natural teeth that have been altered, as by insertion of a long or short coping, to permit the denture to fit over them.

overload
(o´vәr-lōd) an excess over what is normal or needed. iron overload an excess of iron in the body; see hemochromatosis, hemosiderosis, and siderosis. sensory overload a condition in which an individual receives an excessive or intolerable amount o...

overriding
(o″vәr-rīd´ing) the slipping of either part of a fractured bone past the other. extending beyond the usual position.

overripe cataract
hypermature cataract.

overvalued idea
a false or exaggerated belief sustained beyond logic or reason but with less rigidity than a delusion, also often being less patently unbelievable.

overventilation
(o″vәr-ven″tĭ-la´shәn) hyperventilation.

overwear syndrome
(o″ver-wār) extreme photophobia, pain, and lacrimation associated with contact lenses, particularly non–gas permeable hard lenses, usually caused by wearing them excessively. Prolonged lens-induced corneal hypoxia results in corneal epithelial edema and eventually erosion; it can be a chronic cond...

ovicide
(o´vĭ-sīd) an agent destructive to eggs, such as of parasites.

oviduct
(o´vĭ-dәkt) fallopian tube. in nonmammals, a passage through which ova leave the maternal body or pass to an organ communicating with the exterior of the body. adj., ovidu´cal, oviduc´tal., adj.

oviferous
(o-vif´әr-әs) producing ova.

ovigenesis
(o″vĭ-jen´ә-sis) oogenesis.

ovine
(o´vīn) pertaining to, characteristic of, or derived from sheep.

oviparous
(o-vip´ә-rәs) capable of producing eggs in which the embryo develops outside of the maternal body, as in birds.

oviposition
(o″vĭ-po-zi´shәn) the act of laying or depositing eggs.

ovipositor
(o″vĭ-pos´ĭ-tәr) a specialized organ by which many female insects deposit their eggs.

ovolactovegetarian
(o″vo-lak″to-vej″ә-tar´e-әn) a vegetarian who besides foods of vegetable origin will also consume eggs, milk, and milk products. pertaining to such a diet.

ovoplasm
(o´vo-plaz″әm) ooplasm.

ovotestis
(o″vo-tes´tis) a gonad containing both testicular and ovarian tissue.

ovovegetarian
(o″vo-vej″ә-tar´e-әn) a vegetarian who besides foods of vegetable origin will also consume eggs, but not milk or milk products. pertaining to such a diet.

ovoviviparous
(o″vo-vi-vip´ә-rәs) bearing living young that hatch from eggs inside the maternal body, the embryo being nourished by food stored in the egg; lizards are one example.

Ovral
(ōv´ral) trademark for a combination preparation of norgestrel and ethinyl estradiol, used as an oral contraceptive.

ovular
(ov´u-lәr) pertaining to an ovule. pertaining to an oocyte.

ovulation
(ov″u-la´shәn) the discharge of a secondary oocyte (or occasionally more than one) from the graafian follicle; in an adult woman this normally occurs at intervals of about 28 days and alternates between the two ovaries. The discharged oocyte enters the fallopian tube and moves toward the uterus; if it encoun...

ovulation method
cervical mucus method.

ovule
(o´vūl) the oocyte within the graafian follicle. any small, egglike structure.

ovum
(o´vәm) pl. o´va the female reproductive or germ cell, which after fertilization is capable of developing into a new member of the same species; The term ovum is sometimes applied to any stage of the fertilized germ cell during cleavage and even until hatching or birth of the new individual. The human ovum consists...

Owren disease
(o´ren) parahemophilia.

ox warble disease
cutaneous larva migrans (def. 1).

oxacillin
(ok″sә-sil´in) a semisynthetic penicillinase-resistant penicillin used orally or parenterally as the sodium salt in infections due to penicillin-resistant, gram-positive organisms.

oxalate
(ok´sә-lāt) any salt of oxalic acid.

oxalate calculus
a hard urinary calculus of calcium oxalate; some are covered with minute sharp spines that may abrade the renal pelvic epithelium, and others are smooth. Called also calcium oxalate calculus.

oxalemia
(ok″sә-le´me-ә) excess of oxalates in the blood.

oxalic acid
(ok-sal´ik) a poisonous dicarboxylic acid found in various fruits and vegetables, and formed in the metabolism of ascorbic acid and ethylene glycol. While it is not usually a problem with normal diets, it is seen in high concentrations in certain ornamental plants (such as Diffenbachia), as well as in some bleaches and ...

oxalism
(ok´sәl-iz″әm) poisoning by oxalic acid or by an oxalate.

oxaloacetate
(ok″sә-lo-as´ә-tāt) a salt or ester of oxaloacetic acid.

oxaloacetic acid
(ok″sә-lo-ә-se´tik) a metabolic intermediate in the tricarboxylic acid cycle, which is also a substrate of aspartate transaminase.

oxalosis
(ok″sә-lo´sis) generalized deposition of calcium oxalate, in renal and extrarenal tissues, as may occur in primary hyperoxaluria.

oxaluria
(ok″sәl-u´re-ә) hyperoxaluria.

oxamniquine
(oks-am´nĭ-kwin) an anthelmintic agent effective against all stages of infection with Schistosoma mansoni.

oxandrolone
(ok-san´dro-lōn) an androgenic and anabolic steroid that is administered orally in the treatment of catabolic or tissue-wasting diseases or states.

oxaprozin
(ok″sә-pro´zin) a nonsteroidal antiinflammatory drug, used in treatment of arthritis.

oxazepam
(ok-saz´ә-pam) a benzodiazepine used as an antianxiety agent and sometimes used for relief of symptoms of acute alcohol withdrawal.

oxazolidinone
(ok″sә-zo-lid´ĭ-nōn) any of a class of synthetic antibacterial agents effective against gram-positive organisms.

oxcarbazepine
(oks″kahr-baz´ә-pēn) an anticonvulsant used in the treatment of partial seizures, administered orally.

oxiconazole
(ok″sĭ-kon´ә-zōl) a topical antifungal agent used as the nitrate salt in treatment of athlete's foot and ringworm.

oxidant
(ok´sĭ-dәnt) the electron acceptor in an oxidation-reduction (redox) reaction.

oxidase
(ok´sĭ-dās) any of a class of enzymes that catalyze the reduction of molecular oxygen independently of hydrogen peroxide.

oxidation
(ok″sĭ-da´shәn) the act of oxidizing or state of being oxidized. Chemically it consists of the increase of positive charges on an atom or the loss of negative charges. Univalent oxidation indicates loss of one electron; divalent oxidation, the loss of two electrons. The opposite reaction to oxidat...

oxidation number
a number assigned to each atom in a molecule or ion that represents the number of electrons theoretically gained (positive oxidation numbers) or lost (negative numbers) in converting the atom to the elemental form.

oxidation-reduction
(ok″sĭ-da´shәn re-duk´shәn) the chemical reaction whereby electrons are removed (oxidation) from atoms of the substance being oxidized and transferred to those being reduced (reduction). Called also oxidation-reduction reaction and redox reaction.

oxide
(ok´sīd) a compound of oxygen with an element or radical.

oxidize
(ok´sĭ-dīz″) to cause to combine with oxygen or to remove hydrogen.

oxidizing agent
a substance that acts as an electron acceptor in a chemical oxidation-reduction reaction.

oxidoreductase
(ok″sĭ-do-re-duk´tās) a class of enzymes that catalyze the reversible transfer of electrons from one substance to another (oxidation-reduction, or redox reaction).

oxime
(ok´sēm) any of a series of compounds containing the CH(dbondNOH) group, formed by action of hydroxylamine on an aldehyde or ketone.

oximeter
(ok-sim´ә-tәr) a photoelectric device that measures oxygen saturation of the blood by recording the amount of light transmitted or reflected by deoxygenated versus oxygenated hemoglobin. finger oximeter a pulse oximeter whose sensor is attached to a finger, so that the o...

oximetry
(ok-sim´ә-tre) measurement of oxygen saturation of the blood using an oximeter. pulse oximetry a noninvasive method of indicating the arterial oxygen saturation of functional hemoglobin, using a pulse oximeter.

oxolinic acid
(ok-so-lin´ik) a long-acting antibacterial agent, used orally in the treatment of urinary tract infections caused by susceptible gram-negative organisms.

oxprenolol
(oks-pren´ah-lol) a nonselective beta-adrenergic blocking agent, administered orally as the hydrochloride salt in the treatment of hypertension, hypertrophic cardiomyopathy, cardiac arrhythmias, and myocardial infarction.

oxtriphylline
(oks-trif´ә-lēn) the choline salt of theophylline, used as a bronchodilator.

oxybenzone
(ok″se-ben´zōn) a topical sunscreen that absorbs ultraviolet B and some ultraviolet A rays.

oxyblepsia
(ok″se-blep´se-ә) oxyopia.

oxybutynin
(ok″se-bu´tĭ-nin) an anticholinergic and antimuscarinic having direct antispasmodic effects on smooth muscle; used orally as the chloride salt in treatment of uninhibited neurogenic bladder and reflex neurogenic bladder.

oxycephaly
(ok″se-sef´ә-le) a condition in which the top of the skull is pointed or conical owing to premature closure of the coronal and lambdoid sutures. adj., oxycephal´ic., adj.

oxychlorosene
(ok″se-klor´o-sēn) a stabilized organic complex of hypochlorous acid used as a topical antiseptic in the treatment of localized infections.

oxycodone
(ok″se-ko´dōn) an opioid analgesic derived from morphine; used in the form of the hydrochloride and terephthalate salts, administered orally or rectally.

oxygen
(O) (ok´sĭ-jәn) a chemical element, atomic number 8, atomic weight 15.999. It is a colorless and odorless gas that makes up about 20 per cent of the atmosphere. In combination with hydrogen, it forms water; by weight, 90 per cent of water is oxygen. It is the third most abundant of all ...

oxygen analyzer
an instrument that measures the concentration of oxygen in a gas mixture. There are three types of handheld analyzers: physical/paramagnetic, electric, and electrochemical analyzers.

oxygen hood
a device that fits over the head of an infant or small child for administration of oxygen or aerosolized medications.

oxygen poisoning
oxygen toxicity the effects of hyperoxia due to the breathing of high partial pressures of oxygen for prolonged periods; they include serious, sometimes irreversible, damage to the pulmonary capillary endothelium, followed by cerebral edema and convulsions that can be fatal.

oxygen radical
a toxic metabolite of oxygen, such as superoxide or singlet oxygen, capable of damaging microorganisms and normal tissues.

oxygen tension
the partial pressure of oxygen in the blood.

oxygen therapy
a form of respiratory care involving administration of supplemental oxygen for relief of hypoxemia and prevention of damage to the tissue cells as a result of oxygen lack (hypoxia). Oxygen can be toxic and therefore, as with a drug, its dosage and mode of administration are based on an assessment of the needs of the individual ...

oxygenase
(ok´sĭ-jәn-ās) any enzyme of the oxidoreductase class that catalyzes the incorporation of both atoms of molecular oxygen into the substrate.

oxygenation
(ok″sĭ-jә-na´shәn) the act or process of adding oxygen to something. saturation with oxygen. extracorporeal membrane oxygenation(ECMO) a technique of providing respiratory support; the blood is circulated through an artificial lung co...

oxygenator
(ok´sĭ-jә-na″tәr) an apparatus by which oxygen is introduced into the blood during circulation outside the body, as during open-heart surgery. See also heart-lung machine.

oxyhemoglobin
(ok″se-he´mo-glo″bin) hemoglobin combined with molecular oxygen, the form in which oxygen is transported in the blood; its bright red color gives arterial blood its characteristic color.

oxyhemoglobin dissociation curve
a graphic curve representing the normal variation in the amount of oxygen that combines with hemoglobin as a function of the partial pressures of oxygen and carbon dioxide. The curve is said to shift to the right when less than a normal amount of oxygen is taken up by the blood at a given PO2, and to shift to the left whe...

oxymetazoline
(ok″se-mĕ-taz´o-lēn) a vasoconstrictor used topically as the hydrochloride salt in nasal congestion and conjunctival congestion.

oxymetholone
(ok″se-meth´ә-lōn) an anabolic steroid used to treat patients with anemia due to bone marrow failure or deficient red blood cell production and for prophylaxis and treatment of hereditary angioedema; administered orally.

oxymorphone
(ok″se-mor´fōn) an opioid analgesic, used as the hydrochloride salt as an analgesic and adjunct to anesthesia; administered parenterally or rectally.

oxymyoglobin
(ok″se-mi´o-glo″bin) myoglobin charged with oxygen.

oxyntic
(ok-sin´tik) secreting acid, as the parietal (oxyntic) cells.

oxyntic cells
parietal cells.

oxyopia
(ok″se-o´pe-ә) abnormal acuteness of sight; called also oxyblepsia.

oxyphencyclimine
(ok″se-fen-si´klĭ-mēn) an anticholinergic and antimuscarinic with antisecretory, antimotility, and antispasmodic actions; the hydrochloride salt is used in treatment of peptic ulcer and other gastrointestinal disorders.

oxyphil
(ok´se-fil) (in the pl.)Askanazy cells. acidophilic (def. 1).

oxyphil cell tumor
oncocytoma. Hürthle cell tumor.

oxyphil cells
oxyphilic cells acidophilic cells found, along with the more numerous chief cells, in the parathyroid glands. Askanazy cells.