| shear rate | The change in velocity of parallel planes in a flowing fluid separated by unit distance; its units expressed in seconds-1. (05 Mar 2000) |
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| shear stress | The force acting in shear flow expressed per unit area; units in the CGS system: dynes/cm2. (05 Mar 2000) |
| shearbill | <zoology> The black skimmer. See Skimmer. Source: Websters Dictionary (01 Mar 1998) |
| sheared flow | <radiobiology> Fluid flow where the magnitude of the fluid velocity changes along a direction perpedicular to the direction of the fluid flow. (Freeway traffic often exhibits sheared flow in that traffic in the fast lane moves more rapidly than traffic in the slow lane with the exits.) Sheared flow typically correlates with reduced transport and enhanced confinement. (This definition is rather informal and may not be fully technically correct - R.F. Heeter) (09 Oct 1997) |
| shearing | 1. The act or operation of clipping with shears or a shearing machine, as the wool from sheep, or the nap from cloth. 2. The product of the act or operation of clipping with shears or a shearing machine; as, the whole shearing of a flock; the shearings from cloth. 3. Same as Shearling. 4. The act or operation of reaping. 5. The act or operation of dividing with shears; as, the shearing of metal plates. 6. The process of preparing shear steel; tilting. 7. <chemical> The process of making a vertical side cutting in working into a face of coal. Shearing machine. A machine with blades, or rotary disks, for dividing plates or bars of metal. A machine for shearing cloth. Source: Websters Dictionary (01 Mar 1998) |
| shearing edge | The part of an anterior tooth farthest from the apex of the root. Synonym: margo incisalis, cutting edge, incisal margin, incisal surface, shearing edge. (05 Mar 2000) |
| shears | 1. A cutting instrument. Specifically: An instrument consisting of two blades, commonly with bevel edges, connected by a pivot, and working on both sides of the material to be cut, used for cutting cloth and other substances. "Fate urged the shears, and cut the sylph in twain." (Pope) A similar instrument the blades of which are extensions of a curved spring, used for shearing sheep or skins. A shearing machine; a blade, or a set of blades, working against a resisting edge. 2. Anything in the form of shears. Specifically: A pair of wings. An apparatus for raising heavy weights, and especially for stepping and unstepping the lower masts of ships. It consists of two or more spars or pieces of timber, fastened together near the top, steadied by a guy or guys, and furnished with the necessary tackle. Alternative forms: sheers. 3. <machinery> The bedpiece of a machine tool, upon which a table or slide rest is secured; as, the shears of a lathe or planer. Origin: Formerly used also in the singular. Source: Websters Dictionary (01 Mar 1998) |
| sheartail | <ornithology> The common tern. Any one of several species of humming birds of the genus Thaumastura having a long forked tail. (06 Mar 1998) |
| shearwater | <ornithology> Any one of numerous species of long-winged oceanic birds of the genus Puffinus and related genera. They are allied to the petrels, but are larger. The Manx shearwater (P. Anglorum), the dusky shearwater (P. Obscurus), and the greater shearwater (P. Major), are well-known species of the North Atlantic. See Hagdon. Origin: Shear + water; cf. G. Wassersherer; so called from its running lightly along the surface of the water. Source: Websters Dictionary (01 Mar 1998) |
| sheatfish | <zoology> A European siluroid fish (Silurus glanis) allied to the cat-fishes. It is the largest fresh water fish of Europe, sometimes becoming six feet or more in length. See Siluroid. Origin: Cf. Dial. G. Scheid, schaid, schaiden. Source: Websters Dictionary (01 Mar 1998) |
| sheath | A protective covering. The lower part of leaf enveloping stem or culm. A secreted, tubular structure formed around a chain of cells or around a bundle of filaments, cells within a sheath may or may not subsequently separate from the sheath. A layer of outer membrane covering the bacterial flagella. (09 Oct 1997) |
| sheath ligaments | See: fibrous digital sheaths of hand, fibrous digital sheaths of foot, fibrous tendon sheath. (05 Mar 2000) |
| sheath of eyeball | A condensation of connective tissue on the outer aspect of the sclera from which it is separated by a narrow cleftlike episcleral space; the sheath is attached to the sclera near the sclerocorneal junction and blends with the fascia of the extraocular muscles. Synonym: vagina bulbi, capsula bulbi, eye capsule, fascia bulbi, sheath of eyeball, Tenon's capsule, vagina oculi. (05 Mar 2000) |
| sheath of Key and Retzius | <anatomy> The delicate bands of connective tissue among nerve fibres. Origin: NL, fr. Gr. Within + a sinew, nerve. Source: Websters Dictionary (01 Mar 1998) |
| sheath of Schwann | <anatomy> The delicate outer sheath of a nerve fibre; the primitive sheath. The perineurium. Origin: NL, from gr. Nerve + peel, skin. Source: Websters Dictionary (01 Mar 1998) |