| 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) |
| apneustic breathing | Pauses in the respiratory cycle at full inspiration, caused by damage of the respiratory control centres in the more caudal pons. (05 Mar 2000) |
| ataxic breathing | Completely irregular breathing pattern, with continually variable rate and depth of breathing; results from lesions in the respiratory centres in the brainstem, extending from the dorsomedial medulla caudally to the obex. Synonym: ataxic breathing, Biot's breathing, respiratory ataxia. (05 Mar 2000) |
| Biot's breathing | Completely irregular breathing pattern, with continually variable rate and depth of breathing; results from lesions in the respiratory centres in the brainstem, extending from the dorsomedial medulla caudally to the obex. Synonym: ataxic breathing, Biot's breathing, respiratory ataxia. (05 Mar 2000) |
| Biot's breathing sign | <clinical sign> Irregular periods of apnea alternating with four or five deep breaths; seen with increased intracranial pressure. (05 Mar 2000) |
| breathing | 1. Respiration; the act of inhaling and exhaling air. "Subject to a difficulty of breathing." (Melmoth) 2. Air in gentle motion. 3. Any gentle influence or operation; inspiration; as, the breathings of the Spirit. 4. Aspiration; secret prayer. "Earnest desires and breathings after that blessed state." 5. Exercising; promotion of respiration. "Here is a lady that wants breathing too; And I have heard, you knights of Tyre Are excellent in making ladies trip." (Shak) 6. Utterance; communication or publicity by words. "I am sorry to give breathing to my purpose." (Shak) 7. Breathing place; vent. 8. Stop; pause; delay. "You shake the head at so long a breathing." (Shak) 9. Also, in a wider sense, the sound caused by the friction of the outgoing breath in the throat, mouth, etc, when the glottis is wide open; aspiration; the sound expressed by the letter h. 10. A mark to indicate aspiration or its absence. See Rough breathing, Smooth breathing, below. Breathing place. A pause. "That caesura, or breathing place, in the midst of the verse." . A vent. Breathing time, pause; relaxation. Breathing while, time sufficient for drawing breath; a short time. Rough breathing (spiritus asper) . See Asper, Smooth breathing (spiritus lenis), a mark (') indicating the absence of the sound of h, as in 'ienai (ienai). Source: Websters Dictionary (01 Mar 1998) |