| mask | 1. A cover, or partial cover, for the face, used for disguise or protection; as, a dancer's mask; a fencer's mask; a ball player's mask. 2. That which disguises; a pretext or subterfuge. 3. A festive entertainment of dancing or other diversions, where all wear masks; a masquerade; hence, a revel; a frolic; a delusive show. "This thought might lead me through the world's vain mask." (Milton) 4. A dramatic performance, formerly in vogue, in which the actors wore masks and represented mythical or allegorical characters. 5. A grotesque head or face, used to adorn keystones and other prominent parts, to spout water in fountains, and the like; called also mascaron. 6. In a permanent fortification, a redoubt which protects the caponiere. A screen for a battery. 7. <zoology> The lower lip of the larva of a dragon fly, modified so as to form a prehensile organ. Mask house, a house for masquerades. Origin: F. Masque, LL. Masca, mascha, mascus; cf. Sp. & Pg. Mascara, It. Maschera; all fr. Ar. Maskharat buffoon, fool, pleasantry, anything ridiculous or mirthful, fr. Sakhira to ridicule, to laugh at. Cf. Masque, Masquerade. Source: Websters Dictionary (01 Mar 1998) |
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| mask of pregnancy | <medicine> A dark discolouration of the skin, usually local; as, Addison's melasma, or Addison's disease. Melasmic. Origin: NL, fr. Gr. Black spot. Source: Websters Dictionary (01 Mar 1998) |
| mask shell | <zoology> Any spiral marine shell of the genus Persona, having a curiously twisted aperture. Source: Websters Dictionary (01 Mar 1998) |
| Hutchinson's mask | The sensation experienced in tabetic neurosyphilis as if the face were covered with a mask or with cobwebs. (05 Mar 2000) |
| shadow mask | <microscopy> Also Aperture mask. In colour video monitors, a finely perforated or striped metal plate that is located between the three electron guns and the phosphor screen. The mask ensures that the electron beams carrying the R, G, and B signals land on the corresponding phosphors at every point in the picture. (05 Aug 1998) |
| nonrebreathing mask | A mask fitted with both an inhalation valve and an exhalation valve so that all exhaled gas is vented to the external atmosphere and inhaled gas comes only from a reservoir connected to the mask. (05 Mar 2000) |
| ecchymotic mask | A dusky discoloration of the head and neck occurring when the trunk has been subjected to sudden and extreme compression, as in traumatic asphyxia. (05 Mar 2000) |
| tropical mask | A bronze-coloured pigmentation, probably produced by hormone imbalance, occurring in gradually increasing areas on the face, neck, and chest in persons exposed continuously to the tropical sun; similar to chloasma of the temperate zone, but intensified because of strong sunlight. Synonym: tropical mask. (05 Mar 2000) |
| laryngeal mask | A tubular oropharyngeal airway with an inflatable rim at the distal end that when inflated creates an airtight seal immediately above the larynx. (05 Mar 2000) |
| luetic mask | A dirty brownish yellow pigmentation, blotchy in character, resembling that of chloasma, occurring on the forehead, temples, and sometimes the cheeks in patients with tertiary syphilis. (05 Mar 2000) |
| attitude to death | Conceptual response of the individual to the various aspects of death, which are based on his psychosocial and cultural experience. (12 Dec 1998) |
| Black Death | <disease, organism> Yersinina pestis is a gram-negative, rod-shaped, faculatively anaerobic bacterial species in the family Enterobacteriaceae. It causes bubonic plaque, which is transmitted by rodent fleas. Historically known as the Black Plague, this disease devastated Europe and Asia in the 1300s. It still exists today and is characterised by sudden high fever, chills, excessively swollen and tender lymph nodes (buboes), followed by tissue bleeding and gangrene. Other complications include pneumonia and septicaemia. (12 Nov 1997) |
| brain death | Total cessation of brain function for 24 hours as manifested by absence of spontaneous movement, absence of spontaneous respiration, and absence of all brainstem reflexes. (12 Dec 1998) |
| rate, death | The number of deaths in the population divided by the average population (or the population at midyear) is the crude death rate. In 1994, for example, the crude death rate per 1,000 population was 8.8 in the united states, 7.1 in Australia, etc. A death rate can also be tabulated according to age or cause. (12 Dec 1998) |
| genetic death | Death of the bearer of a gene at any age before generating living offspring. May be compatible with good health and long life. See: genetic lethal. (05 Mar 2000) |