| pyr | 1. <abbreviation> Pyrimidine, pyroglutamic acid. 2. <chemistry, prefix> Combining forms designating fire or heat; specifically, used to imply an actual or theoretical derivative by the action of heat; as in pyrophosphoric, pyrosulphuric, pyrotartaric, pyrotungstic, etc. Origin: Gr, fire. (29 Oct 1998) |
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| pyracanth | <botany> The evergreen thorn (Crataegus Pyracantha), a shrub native of Europe. Origin: Gr. Fire + a thorn, prickly plant. Source: Websters Dictionary (01 Mar 1998) |
| pyracin | Pyridoxolactone, the lactone of 4-pyridoxic acid. (05 Mar 2000) |
| pyralid | <zoology> Any moth of the family Pyralidae. The species are numerous and mostly small, but some of them are very injurious, as the bee moth, meal moth, hop moth, and clover moth. Origin: L. Pyralis, -idis, a kind of winged insect. Source: Websters Dictionary (01 Mar 1998) |
| pyramid | 1. A solid body standing on a triangular, square, or polygonal base, and terminating in a point at the top; especially, a structure or edifice of this shape. 2. <geometry> A solid figure contained by a plane rectilineal figure as base and several triangles which have a common vertex and whose bases are sides of the base. 3. The game of pool in which the balls are placed in the form of a triangle at spot. <geometry> Altitude of a pyramid a pyramid whose axis is perpendicular to the base. Origin: L. Pyramis, -idis, fr. Gr, of Egyptian origin: cf. F. Pyramide. Source: Websters Dictionary (01 Mar 1998) |
| pyramid of light | A triangular area at the anterior inferior part of the tympanic membrane, running from the umbo to the periphery, where there is seen a bright reflection of light. Synonym: cone of light, light reflex, Politzer's luminous cone, red reflex, Wilde's triangle. Malacarne's pyramid, a lobule on the undersurface of the cerebellum, the posterior portion of the vermis. (05 Mar 2000) |
| pyramid of medulla oblongata | An elongated, white prominence on the ventral surface of the medulla oblongata on either side along the anterior median fissure, corresponding to the pyramidal tract. Synonym: pyramis medullae oblongatae, anterior column of medulla oblongata, anterior pyramid. (05 Mar 2000) |
| pyramid of thyroid | <anatomy> An inconstant narrow lobe of the thyroid gland that arises from the upper border of the isthmus and extends upward, sometimes as far as the hyoid bone; it marks the point of continuity with the thyroglossal duct. Synonym: lobus pyramidalis glandulae thyroideae, Lallouette's pyramid, Morgagni's appendix, pyramid of thyroid. (05 Mar 2000) |
| pyramid of tympanum | A conical projection posterior to the vestibular window in the middle ear; it is hollow and contains the stapedius muscle. Synonym: pyramid of tympanum, pyramidal eminence, pyramis tympani. (05 Mar 2000) |
| pyramid of vermis | A subdivision of the inferior vermis of the cerebellum between the tuber and the uvula. Synonym: pyramis vermis, cerebellar pyramid. Pyramid of vestibule, the upper triangular extremity of the crista vestibuli. Synonym: pyramis vestibuli. (05 Mar 2000) |
| pyramid sign | <clinical sign> Any of the symptoms indicating a morbid condition of the pyramidal tracts, such as the Babinski or Gordon sign, spastic spinal paralysis, foot clonus, etc. (05 Mar 2000) |
| pyramidal | 1. Of or pertaining to a pyramid; in the form of a a pyramid; pyramidical; as, pyramidal cleavage. "The mystic obelisks stand up Triangular, pyramidal." (Mrs. Browning) 2. <chemistry> Same as Tetragonal. <mathematics> Pyramidal numbers, certain series of figurate numbers expressing the number of balls or points that may be arranged in the form of pyramids. Thus 1, 4, 10, 20, 35, etc, are trangular pyramidal numbers; and 1, 5, 14, 30, 55, etc, are square pyramidal numbers. Origin: Cf. F. Pyramidal. <anatomy> One of the carpal bones. See Cuneiform, 2 . Source: Websters Dictionary (01 Mar 1998) |
| pyramidal auricular muscle | <anatomy> An occasional prolongation of the fibres of the tragicus to the spina helicis. Synonym: musculus pyramidalis auriculae, Jung's muscle, pyramidal muscle of auricle. (05 Mar 2000) |
| pyramidal bone | A bone on the medial (ulnar) side of the proximal row of the carpus, articulating with the lunate, pisiform, and hamate. Synonym: os triquetrum, cubital bone, os pyramidale, os triangulare, pyramidal bone, pyramidale, three-cornered bone, triquetrum. (05 Mar 2000) |
| pyramidal cataract | A cone-shaped, anterior polar cataract. (05 Mar 2000) |