An increase in the volume of a substance while its mass remains the same. Expansion is usually due to heating. When substances are heated, the molecular bonds between their particles are weakened, and the particles move faster, causing the substance to expand.
A number or other mathematical expression written in an extended form. For example, a2 + 2ab + b2 is the expansion of (a + b)2.
Main Entry: ex·pan·sion Pronunciation: ik-'span-ch&n Function: noun 1: the act or process of expanding <localized pain along
nerve trunks may be due to the expansion of the dissolved nitrogen without actual bubble formation —H. G. Armstrong> 2: the quality or state of being expanded
The phase of the business cycle when the economy moves from a trough to a peak. It is a period when business activity surges and gross domestic product expands until it
reaches a peak. Also known as an "economic recovery".
Investopedia Commentary
An expansion is one of two basic business cycle phases. The other is contraction. The
transition from expansion to contraction is termed a "peak" and the changeover from contraction to expansion is a trough. Expansions last on average about three to four years but have been known to
last anywhere from 12 months to more than 10 years. Much of the '60s was a time of expansion which lasted almost nine years.
Cut"-off`\ (k[u^]t"[o^]f`; 115), n. 1. That which cuts off or shortens, as a nearer passage or road. 2. (Mach.) (a) The valve gearing or mechanism by which steam is cut off from entering the cylinder of a steam engine after a definite point in a stroke, so as to allow the remainder of the stroke to be made by the expansive force of the steam already let in. See Expansion gear, under Expansion. (b) Any device for stopping or changing a current, as of grain or water in a spout.
Ex*pand"\, v. t. [imp. & p. p. Expanded; p. pr. & vb. n. Expanding.] [L. expandere, expansum; ex out + pandere to spread out, to throw open; perh. akin to E. patent. Cf. Spawn.]1. To lay open by extending; to open wide; to spread out; to diffuse; as, a flower expands its leaves. Then with expanded wings he steers his flight. --Milton. 2. To cause the particles or parts of to spread themselves or stand apart, thus increasing bulk without addition of substance; to make to occupy more space; to dilate; to distend; to extend every way; to enlarge; -- opposed to contract; as, to expand the chest; heat expands all bodies; to expand the sphere of benevolence. 3. (Math.) To state in enlarged form; to develop; as, to expand an equation. See Expansion, 5.
Ex*pan"sion\, n. [L. expansio: cf. F. expansion.]1. The act of expanding or spreading out; the condition of being expanded; dilation; enlargement. 2. That which is expanded; expanse; extend surface; as, the expansion of a sheet or of a lake; the expansion was formed of metal. The starred expansion of the skies. --Beattie. 3. Space through which anything is expanded; also, pure space. Lost in expansion, void and infinite. --Blackmore. 4. (Com.) Enlargement or extension of business transactions; esp., increase of the circulation of bank notes. 5. (Math.) The developed result of an indicated operation; as, the expansion of (a + b)^2 is a^2 + 2ab + b^2. 6. (Steam Engine) The operation of steam in a cylinder after its communication with the boiler has been cut off, by which it continues to exert pressure upon the moving piston. 7. (Nav. Arch.) The enlargement of the ship mathematically from a model or drawing to the full or building size, in the process of construction. --Ham. Nav. Encyc. Note: Expansion is also used adjectively, as in expansion joint, expansion gear, etc. Expansion curve, a curve the co["o]rdinates of which show the relation between the pressure and volume of expanding gas or vapor; esp. (Steam engine), that part of an indicator diagram which shows the declining pressure of the steam as it expands in the cylinder. Expansion gear (Steam Engine). a cut-off gear. See Illust. of Link motion. Automatic expansion gear or cut-off, one that is regulated by the governor, and varies the supply of steam to the engine with the demand for power. Fixed expansion gear, or Fixed cut-off, one that always operates at the same fixed point of the stroke. Expansion joint, or Expansion coupling (Mech. & Engin.), a yielding joint or coupling for so uniting parts of a machine or structure that expansion, as by heat, is prevented from causing injurious strains; as by heat, is prevented from causing injurious strains; as: (a) A side or set of rollers, at the end of bridge truss, to support it but allow end play. (b) A telescopic joint in a steam pipe, to permit one part of the pipe to slide within the other. (c) A clamp for holding a locomotive frame to the boiler while allowing lengthwise motion. Expansion valve (Steam Engine), a cut-off valve, to shut off steam from the cylinder before the end of each stroke.
Gear\, n. [OE. gere, ger, AS. gearwe clothing, adornment, armor, fr. gearo, gearu, ready, yare; akin to OHG. garaw[=i], garw[=i] ornament, dress. See Yare, and cf. Garb dress.]1. Clothing; garments; ornaments. Array thyself in thy most gorgeous gear. --Spenser. 2. Goods; property; household stuff. --Chaucer. Homely gear and common ware. --Robynson (More's Utopia). 3. Whatever is prepared for use or wear; manufactured stuff or material. Clad in a vesture of unknown gear. --Spenser. 4. The harness of horses or cattle; trapping. 5. Warlike accouterments. [Scot.] --Jamieson. 6. Manner; custom; behavior. [Obs.] --Chaucer. 7. Business matters; affairs; concern. [Obs.] Thus go they both together to their gear. --Spenser. 8. (Mech.) (a) A toothed wheel, or cogwheel; as, a spur gear, or a bevel gear; also, toothed wheels, collectively. (b) An apparatus for performing a special function; gearing; as, the feed gear of a lathe. (c) Engagement of parts with each other; as, in gear; out of gear. 9. pl. (Naut.) See 1st Jeer (b) . 10. Anything worthless; stuff; nonsense; rubbish. [Obs. or Prov. Eng.] --Wright. That servant of his that confessed and uttered this gear was an honest man. --Latimer. Bever gear. See Bevel gear. Core gear, a mortise gear, or its skeleton. See Mortise wheel, under Mortise. Expansion gear (Steam Engine), the arrangement of parts for cutting off steam at a certain part of the stroke, so as to leave it to act upon the piston expansively; the cut-off. See under Expansion. Feed gear. See Feed motion, under Feed, n. Gear cutter, a machine or tool for forming the teeth of gear wheels by cutting. Gear wheel, any cogwheel. Running gear. See under Running. To throwin, or out of, gear (Mach.), to connect or disconnect (wheelwork or couplings, etc.); to put in, or out of, working relation.
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