| dental lever | One who, or that which, raises or lifts up anything; as: A mechanical contrivance, usually an endless belt or chain with a series of scoops or buckets, for transferring grain to an upper loft for storage. A cage or platform and the hoisting machinery in a hotel, warehouse, mine, etc, for conveying persons, goods, etc, to or from different floors or levels; called in England a lift; the cage or platform itself. A building for elevating, storing, and discharging, grain. <anatomy> An instrument for raising a depressed portion of a bone. Elevator head, leg, and boot, the boxes in which the upper pulley, belt, and lower pulley, respectively, run in a grain elevator. Origin: L, one who raises up, a deliverer: cf. F. Elevateur. Source: Websters Dictionary (01 Mar 1998) |
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| lever | 1. <mechanics> A rigid piece which is capable of turning about one point, or axis (the fulcrum), and in which are two or more other points where forces are applied; used for transmitting and modifying force and motion. Specif, a bar of metal, wood, or other rigid substance, used to exert a pressure, or sustain a weight, at one point of its length, by receiving a force or power at a second, and turning at a third on a fixed point called a fulcrum. It is usually named as the first of the six mechanical powers, and is three kinds, according as either the fulcrum F, the weight W, or the power P. Respectively, is situated between the other two, as in the figures. 2. <machinery> A bar, as a capstan bar, applied to a rotatory piece to turn it. An arm on a rock shaft, to give motion to the shaft or to obtain motion from it. Compound lever, a machine consisting of two or more levers acting upon each other. Lever escapement. See Escapement. Lever jack. See Jack. Lever watch, a watch having a vibrating lever to connect the action of the escape wheel with that of the balance. Universal lever, a machine formed by a combination of a lever with the wheel and axle, in such a manner as to convert the reciprocating motion of the lever into a continued rectilinear motion of some body to which the power is applied. Origin: OE. Levour, OF. Leveor, prop, a lifter, fr. F. Lever to raise, L. Levare; akin to levis light in weight, E. Levity, and perh. To E. Light not heavy: cf. F. Levier. Cf. Alleviate, Elevate, Leaven, Legerdemain, Levy. Source: Websters Dictionary (01 Mar 1998) |
| cannula | <equipment> A tube for insertion into a duct or cavity, during insertion its lumen is usually occupied by a trocar. (18 Nov 1997) |
| perfusion cannula | A double-barreled cannula used for irrigation of a cavity, the wash fluid passing into the cavity through one tube and out through the other. Washout cannula, a cannula that can be irrigated without removal from the artery. (05 Mar 2000) |
| laparoscopic cannula | hasson cannula |
| air-lock | <microscopy> An intermediate, enclosed chamber of a vacuum or pressure system through which an object may be passed without effectively changing the vacuum or pressure of the main body of the system. Reference here is to the vacuum of all electron microscopes. (05 Aug 1998) |
| key-in-lock manoeuvre | A method by which obstetrical forceps are used to rotate the foetal head. Synonym: DeLee's manoeuvre. (05 Mar 2000) |
| lock | 1. Anything that fastens; specifically, a fastening, as for a door, a lid, a trunk, a drawer, and the like, in which a bolt is moved by a key so as to hold or to release the thing fastened. 2. A fastening together or interlacing; a closing of one thing upon another; a state of being fixed or immovable. "Albemarle Street closed by a lock of carriages." (De Quincey) 3. A place from which egress is prevented, as by a lock. 4. The barrier or works which confine the water of a stream or canal. 5. An inclosure in a canal with gates at each end, used in raising or lowering boats as they pass from one level to another; called also lift lock. 6. That part or apparatus of a firearm by which the charge is exploded; as, a matchlock, flintlock, percussion lock, etc. 7. A device for keeping a wheel from turning. 8. A grapple in wrestling. Detector lock, a lock containing a contrivance for showing whether it as has been tampered with. Lock bay, a range of bond stone. Mortise lock, a door lock inserted in a mortise. Rim lock, a lock fastened to the face of a door, thus differing from a mortise lock. Origin: AS. Loc inclosure, an inclosed place, the fastening of a door, fr. Lucan to lock, fasten; akin to OS. Lukan (in comp), D. Luiken, OHG. Luhhan, Icel. Lka, Goth. Lukan (in comp); cf. Skr. Ruj to break. Cf. Locket. Source: Websters Dictionary (01 Mar 1998) |
| lock-and-key model | A model used to suggest the mode of operation of an enzyme in which the substrate fits into the active site of the protein like a key into a lock. (05 Mar 2000) |
| lock and key models | <chemistry, immunology> Specific recognition in biological systems might be mediated through interactions that depend upon very precise steric matching between receptor and ligand or between enzyme and substrate. The commonly used analogy is between lock and key and implies a precise sterically determined interaction. (18 Nov 1997) |
| lock finger | An affection in which the movement of the finger is arrested for a moment in flexion or extension and then continues with a jerk. Synonym: jerk finger, lock finger, snap finger, spring finger, stuck finger. (05 Mar 2000) |
| lock hospital | A hospital for the treatment of venereal diseases. Source: Websters Dictionary (01 Mar 1998) |
| lock step | A mode of marching by a body of men going one after another as closely as possible, in which the leg of each moves at the same time with the corresponding leg of the person before him. Source: Websters Dictionary (01 Mar 1998) |