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poison ivy

(ī′vē) A climbing vine, Toxicodendron radicans, that on contact may produce severe pruritic dermatitis. Toxicodendron species contain urushiol, an extremely irritating oily resin, which stimulates a hypersensitivity reaction. First contact produces sensitization; later contacts cause severe blistering, eczema, and itching. SEE: poison ivy dermatitis.

poison oak

A climbing vine, Toxicodendron diversiloba, closely related to poison ivy and having the same active substances. SEE: illus.






(poy′zŏn-ŭs) [L. potio, a poisonous draft] Having the properties or qualities of a poison. SYN: toxic; venomous.

poisonous plants

Plants containing a poisonous substance that may be fatal if ingested, including azalea, castor bean, chinaberry, European bittersweet, wild or black cherry, oleander, berries of holly and mistletoe, dieffenbachia, horse chestnuts, poison hemlock, laurel, death cup, black nightshade or deadly nightshade, rhododendron, choke cherry, Japanese yew, unripe fruit of akee, cassava roots, betel nut, seeds and pods of bird-of-paradise, belladonna, angels trumpet, fava bean (if eaten by a person with glucose-6-phosphate deficiency), foxglove, bulb of hyacinth, Indian tobacco, iris root, poinsettia, pokeroot, apricot kernels, apple seeds, green tubers and new sprouts of potatoes, privet, rhubarb leaves, wild tomatoes, skunk cabbage, and jimsonweed; and plants containing irritating substances, such as poison ivy, poison oak, and poison sumac.

Poland syndrome

(pō′lĭnd) A rare developmental anomaly in which one pectoralis muscle and the fingers on the same side of the body are hypoplastic or aplastic. The disease is not genetically transmitted but occurs spontaneously.


[L. polaris] Pert. to a pole.

polar body

SEE: under body.


(pō″lă-rĭm′ĕ-tĕr) [″ + Gr. metron, measure] An instrument for measuring amount of polarization of light or rotation of polarized light.


(pō″lăr-ĭm′ĕ-trē) The measurement of the amount and rotation of polarized light.


(pō-lăr′ĭ-tē) 1. The quality of having poles. 2. The exhibition of opposite effects at the two extremities in physical therapy. 3. The positive or negative state of an electrical battery. 4. In cell division, the relation of cell constituents to the poles of the cell.


(pō″lă-rĭ-zā′shŏn) 1. A condition in a ray of light in which vibrations occur in only one plane. 2. In a galvanic battery, collection of hydrogen bubbles on the negative plate and oxygen on the positive plate, whereby generation of current is impeded. 3. The electrical state that exists at the cell membrane of an excitable cell at rest, in which the inside is negatively charged in ...

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