| lac | A resinous substance produced mainly on the banyan tree, but to some extent on other trees, by the Coccus lacca, a scale-shaped insect, the female of which fixes herself on the bark, and exudes from the margin of her body this resinous substance. Stick-lac is the substance in its natural state, incrusting small twigs. When broken off, and the colouring matter partly removed, the granular residuum is called seed-lac. When melted, and reduced to a thin crust, it is called shell-lac or shellac. Lac is an important ingredient in sealing wax, dyes, varnishes, and lacquers. Ceylon lac, a resinous exudation of the tree Croton lacciferum, resembling lac. Lac dye, a scarlet dye obtained from stick-lac. Lac lake, the colouring matter of lac dye when precipitated from its solutions by alum. Mexican lac, an exudation of the tree Croton Draco. Origin: Per. Lak; akin to Skr. Laksha: cf. F. Lague, It. & NL. Lacca. Cf. Lake a colour, Lacquer, Litmus. Source: Websters Dictionary (01 Mar 1998) |
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| Lac operon | Group of adjacent and coordinately controlled genes concerned with the metabolism of lactose in E. Coli. The lac operon was the first example of a group of genes under the control of an operator region to which a lactose repressor binds. When the bacteria are transferred to lactose containing medium, allolactose (which forms by transglycosylation when lactose is present in the cell) binds to the repressor, inhibits the binding of the repressor to the operator and allows transcription of mRNA for enzymes involved in galactose metabolism and transport across the membrane (_ galactosidase, galactoside permease and thiogalactoside transacetylase). (18 Nov 1997) |
| lac sulfuris | Sublimed sulfur boiled with lime water, the lime being removed from the precipitate by washing with diluted hydrochloric acid; used in preparing sulfur ointment and in the treatment of various skin disorders. Synonym: lac sulfuris, milk of sulfur. (05 Mar 2000) |
| lac vaccinum | Cow's milk. (05 Mar 2000) |
| lacca | A resinous excretion of an insect, Laccifer (Tachardia) lacca (family Coccidae). The insects suck the juice of various resiniferous Asiatic (chiefly Indian) trees and excrete and deposit "stick-lac." shellac softens at a low temperature. It has many nonmedicinal uses and is also used to coat confections and tablets and in dental materials, e.g., impression compound and denture base plates. Synonym: lacca. (05 Mar 2000) |
| laccase | <enzyme> An enzyme oxidizing benzenediols to semiquinones with O2. Synonym: monophenol monooxygenase, phenol oxidase, phenolase, polyphenol oxidase, urushiol oxidase. (05 Mar 2000) |
| laccic | <chemistry> Pertaining to lac, or produced from it; as, laccic acid. Origin: Cf. F. Laccique. Source: Websters Dictionary (01 Mar 1998) |
| laccin | <chemistry> A yellow amorphous substance obtained from lac. Origin: Cf. F. Laccine. Source: Websters Dictionary (01 Mar 1998) |
| laccolith | <geology> A mass of igneous rock intruded between sedimentary beds and resulting in a mammiform bulging of the overlying strata. Laccolitic. Origin: Gr. A cistern, -lith. Source: Websters Dictionary (01 Mar 1998) |
| lace | 1. That which binds or holds, especially by being interwoven; a string, cord, or band, usually one passing through eyelet or other holes, and used in drawing and holding together parts of a garment, of a shoe, of a machine belt, etc. "His hat hung at his back down by a lace." (Chaucer) "For striving more, the more in laces strong Himself he tied." (Spenser) 2. A snare or gin, especially one made of interwoven cords; a net. "Vulcanus had caught thee [Venus] in his lace." (Chaucer) 3. A fabric of fine threads of linen, silk, cotton, etc, often ornamented with figures; a delicate tissue of thread, much worn as an ornament of dress. "Our English dames are much given to the wearing of costlylaces." (Bacon) 4. Spirits added to coffee or some other beverage. Alencon lace, a kind of point lace, entirely of needlework, first made at Alencon in France, in the 17th century. It is very durable and of great beauty and cost. Bone lace, Brussels lace, etc. See Bone, Brussels, etc. Gold lace, or Silver lace, lace having warp threads of silk, or silk and cotton, and a weft of silk threads covered with gold (or silver), or with gilt. Lace leather, thin, oil-tanned leather suitable for cutting into lacings for machine belts. <zoology> Lace lizard, the main piece of timber which supports the beak or head projecting beyond the stem of a ship. Lace pillow, and Pillow lace. See Pillow. Origin: OE. Las, OF. Laz, F. Lacs, dim. Lacet, fr. L. Laqueus noose, snare; prob. Akin to lacere to entice. Cf. Delight, Elicit, Lasso, Latchet. Source: Websters Dictionary (01 Mar 1998) |
| lace-bark | <botany> A shrub in the West Indies (Lagetta Iintearia); so called from the lacelike layers of its inner bark. Source: Websters Dictionary (01 Mar 1998) |
| lace-winged | <zoology> Having thin, transparent, reticulated wings; as, the lace-winged flies. Source: Websters Dictionary (01 Mar 1998) |
| lacerable | Capable of being, or liable to be, torn. Origin: L. Lacero, to tear to pieces, fr. Lacer, mangled (05 Mar 2000) |
| lacerate | To cut. (27 Sep 1997) |
| lacerated | 1. Rent; torn; mangled; as, a lacerated wound. "By each other's fury lacerate" (Southey) 2. <botany> Jagged, or slashed irregularly, at the end, or along the edge. Origin: L. Laceratus, p. P. Source: Websters Dictionary (01 Mar 1998) |
| seed-lac | A species of lac. See the Note under Lac. Source: Websters Dictionary (01 Mar 1998) |
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