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(prō-nā′tŏr) A muscle that pronates.


(prōn) 1. Horizontal with the face downward. 2. Denoting the hand with the palm turned downward. It is the opposite of supine. SYN: prone posture; procumbent.


Plural of pronephros.


(prō-nef′rŏs, prō-nef′ros″, prō-nef′roy″) pl. pronephroi [pro- + nephros] The earliest and simplest type of excretory organ of vertebrates, functional in simpler forms (cyclostomes), and serving as a provisional kidney in some fishes and amphibians. In reptiles, birds, and mammals, it appears in the embryo as a temporary, functionless structure. SEE: mesonephros; metanephros.


(prō-noor′ăl) [pro- + neural] Pert. to any biochemical, cell, reaction, or tissue that gives rise to or promotes the development of nerves.


(prong) 1. A cone-shaped body such as the root of a tooth. 2. A forkshaped object, such as a nasal cannula.


(prōn′ing) [prone] Placing a patient, esp. one in respiratory failure resulting from acute respiratory distress syndrome (ARDS), face down, in a prone position.

PATIENT CARE: Proning is used to improve oxygenation and reduce mortality in ARDS. No benefit on reducing mortality has been demonstrated.


(prō-nor′mō-blăst) [Gr. pro, before, + L. norma, rule, + Gr. blastos, germ] An early precursor of the red blood cell.


(prō-nu′klē-ŭs) [Gr. pro, before, + nucleus, little kernel] The haploid nucleus of either the ovum or spermatozoon prior to their union in fertilization.

proof of concept

An early scientific investigation of an idea; a pilot project.


(proof′rēd″ing) In genetics and cellular biology, the ability of a cell to ensure that copies of its genetic information are faithfully made with limited errors or mutations.


(prō-ŏt′ĭk,-ō′tĭk) [″ + ous, ear] In front of the ear.


A device of sturdy material used to support or hold something in place.

mouth p. A metal or rubber device inserted between the jaws to maintain the mouth in an open position. SYN: bite block.


(prop′ă-gāt″) [L. propagare, to fasten down, set slips, propagate] 1. To transmit or spread through a population, e.g., an infection or epidemic illness. 2. To reproduce a species with a particular genotype or phenotype. 3. To spread through a medium or part of the body, ...

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