18-letter words containing a, c, r, s
- astrological chart — map of constellations at certain time
- astrometric binary — a binary star that can be recognized as such because of its undulating proper motion.
- astronomical clock — a complex clock showing astronomical phenomena, such as the phases of the moon
- asymmetric warfare — warfare in which opposing groups or nations have unequal military resources, and the weaker opponent uses unconventional weapons and tactics, as terrorism, to exploit the vulnerabilities of the enemy.
- asymptotic freedom — a property of the force between quarks, according to quantum chromodynamics, such that they behave almost like free particles when they are close together within a hadron.
- asynchronous logic — (architecture) A data-driven circuit design technique where, instead of the components sharing a common clock and exchanging data on clock edges, data is passed on as soon as it is available. This removes the need to distribute a common clock signal throughout the circuit with acceptable clock skew. It also helps to reduce power dissipation in CMOS circuits because gates only switch when they are doing useful work rather than on every clock edge. There are many kinds of asynchronous logic. Data signals may use either "dual rail encoding" or "data bundling". Each dual rail encoded Boolean is implemented as two wires. This allows the value and the timing information to be communicated for each data bit. Bundled data has one wire for each data bit and another for timing. Level sensitive circuits typically represent a logic one by a high voltage and a logic zero by a low voltage whereas transition signalling uses a change in the signal level to convey information. A speed independent design is tolerant to variations in gate speeds but not to propagation delays in wires; a delay insensitive circuit is tolerant to variations in wire delays as well. The purest form of circuit is delay-insensitive and uses dual-rail encoding with transition signalling. A transition on one wire indicates the arrival of a zero, a transition on the other the arrival of a one. The levels on the wires are of no significance. Such an approach enables the design of fully delay-insensitive circuits and automatic layout as the delays introduced by the layout compiler can't affect the functionality (only the performance). Level sensitive designs can use simpler, stateless logic gates but require a "return to zero" phase in each transition.
- at/from a distance — If you are at a distance from something, or if you see it or remember it from a distance, you are a long way away from it in space or time.
- athletic supporter — jockstrap
- atmospheric engine — an early form of single-acting engine in which the power stroke is provided by atmospheric pressure acting upon a piston in an exhausted cylinder.
- atmospheric window — wavelengths of the electromagnetic spectrum that can be transmitted through the earth's atmosphere. Atmospheric windows occur in the visible, infrared, and radio regions of the spectrum
- attendance figures — the number of people present at events such as football matches or concerts
- auditory phonetics — the branch of phonetics concerned with the perception of speech sounds by humans
- australopithecines — Plural form of australopithecine.
- automatic exposure — the automatic adjustment of the lens aperture and shutter speed of a camera by a control mechanism
- aviation insurance — Aviation insurance is insurance cover for aircraft, and for damage, injury, or loss of life or cargo while traveling on aircraft.
- bachelor's-buttons — any of various plants of the daisy family with button-like flower heads
- back to square one — If you are back to square one, you have to start dealing with something from the beginning again because the way you were dealing with it has failed.
- backus normal form — Backus-Naur Form
- balanced scorecard — A balanced scorecard is a type of management report which includes both financial and non-financial measures.
- ballistocardiogram — a tracing made by a ballistocardiograph
- banker's reference — a confidential statement about the financial status of a customer, provided by one bank to another, or to an authorized enquirer
- bankers-acceptance — a draft or bill of exchange that a bank has accepted. Abbreviation: BA. Also called banker's acceptance. Compare acceptance (def 6).
- basal conglomerate — a conglomerate deposited on an erosion surface and constituting the bottom layer of a stratigraphic series.
- basket-handle arch — an arch having a symmetrical form drawn from an odd number of radii in excess of one, which increase in length from the springing toward the center.
- behavioral science — any of several studies, as sociology, psychology, anthropology, etc., that examine human activities in an attempt to discover recurrent patterns and to formulate rules about social behavior
- benchmark position — a public service job used for comparison with a similar position, such as a position in commerce, for wage settlements
- bichromate process — any of several methods of photography in which the light-sensitive medium is alkaline bichromate associated with a colloid such as gum, albumen, or gelatin.
- biodiversification — the process by which the diversity of plants or animals develops or is increased within a particular region or group of organisms.
- biological parents — the biological mother and father of a child
- biz-core stability — (security) Internet security products which secure the business core.
- black lives matter — a political and social movement originating among African Americans, emphasizing basic human rights and racial equality for black people and campaigning against various forms of racism. Abbreviations: BLM, B.L.M.
- black-necked stork — a large Australian stork, Xenorhyncus asiaticus, having a white plumage, dark green back and tail, and red legs
- blissful ignorance — unawareness or inexperience of something unpleasant
- board of directors — A company's board of directors is the group of people elected by its shareholders to manage the company.
- board of elections — a bipartisan board appointed usually by local authorities and charged with control of elections and voting procedure.
- borosilicate glass — any of a range of heat- and chemical-resistant glasses, such as Pyrex, prepared by fusing together boron(III) oxide, silicon dioxide, and, usually, a metal oxide
- branch instruction — a machine-language or assembly-language instruction that causes the computer to branch to another instruction
- branch to fishkill — (IBM: from the location of one of the corporation's facilities) Any unexpected jump in a program that produces catastrophic or just plain weird results. See jump off into never-never land, hyperspace.
- breach of security — an act that violates a country, area, or building's security measures
- bread and circuses — something offered as a means of distracting attention from a problem or grievance
- break your silence — If someone breaks their silence about something, they talk about something that they have not talked about before or for a long time.
- breast enhancement — a surgical procedure to increase the size of a woman's breasts
- breathing exercise — an exercise intended to promote effective and healthy breathing and breath control
- brewer's blackbird — a blackbird, Euphagus cyanocephalus, of the U.S., the male of which has greenish-black plumage with a purplish-black head.
- broadcasting house — any of a number of buildings in the UK from which the BBC broadcasts or has broadcast
- bronchocandidiasis — See under candidiasis.
- bursa of fabricius — a lymphoid gland of the cloaca in birds, believed to function in disease resistance, and closing or disappearing as the bird ages.
- cabernet sauvignon — a black grape originally grown in the Bordeaux area of France, and now throughout the wine-producing world
- california fuchsia — a North American onagraceous plant, Zauschneria californica, with tubular scarlet flowers
- california rosebay — a Pacific coast shrub or tree (Rhododendron californicum) of the heath family, with rosy or purplish flowers