20-letter words containing i, r, t
- auxiliary power unit — an additional engine fitted to an aircraft to operate when the main engines are not in use
- axiomatic set theory — (theory) One of several approaches to set theory, consisting of a formal language for talking about sets and a collection of axioms describing how they behave. There are many different axiomatisations for set theory. Each takes a slightly different approach to the problem of finding a theory that captures as much as possible of the intuitive idea of what a set is, while avoiding the paradoxes that result from accepting all of it, the most famous being Russell's paradox. The main source of trouble in naive set theory is the idea that you can specify a set by saying whether each object in the universe is in the "set" or not. Accordingly, the most important differences between different axiomatisations of set theory concern the restrictions they place on this idea (known as "comprehension"). NBG (von Neumann-Bernays-Goedel) set theory sort of allows comprehension for all formulae without restriction, but distinguishes between two kinds of set, so that the sets produced by applying comprehension are only second-class sets. NBG is exactly as powerful as ZF, in the sense that any statement that can be formalised in both theories is a theorem of ZF if and only if it is a theorem of ZFC. MK (Morse-Kelley) set theory is a strengthened version of NBG, with a simpler axiom system. It is strictly stronger than NBG, and it is possible that NBG might be consistent but MK inconsistent. ML ("Modern Logic") is to NF as NBG is to ZF. (Its name derives from the title of the book in which Quine introduced an early, defective, form of it). It is stronger than ZF (it can prove things that ZF can't), but if NF is consistent then ML is too.
- background radiation — low-intensity radiation from, for example, small amounts of radioisotopes in soil, air, building materials, etc
- backwards compatible — backward compatibility
- bacteriochlorophylls — Plural form of bacteriochlorophyll.
- ballet-wrap cardigan — a cardigan with wrapover fronts which are fastened with wraparound ties
- ballistic trajectory — the path of an unpowered object, as a missile, moving only under the influence of gravity and possibly atmospheric friction and with its surface providing no significant lift to alter the course of flight.
- baptism for the dead — the baptism of a living person in the place of and for the sake of one who has died unbaptized: now practiced chiefly by Mormons.
- bartramian sandpiper — upland sandpiper.
- basal metabolic rate — the rate at which heat is produced by the body at rest, 12 to 14 hours after eating, measured in kilocalories per square metre of body surface per hour
- basic lead carbonate — ceruse.
- basic object adapter — (architecture) (BOA) Part of the CORBA architecture.
- basic rate interface — (communications) (BRI, 2B+D, 2B1D) An Integrated Services Digital Network channel consisting of two 64 kbps "bearer" (B) channels and one 16 kbps "delta" (D) channel, giving a total data rate of 144 kbps. The B channels are used for voice or user data, and the D channel is used for control and signalling and/or X.25 packet networking. BRI is the kind of ISDN interface most likely to be found in residential service.
- bats-wing coral-tree — a small tree, Erythrina verspertilio, of tropical and subtropical Australia with red flowers and leaves shaped like the wings of a bat
- be (or get) wise to — to be (or become) aware of; have (or attain) a proper understanding of
- be for the high jump — to be liable to receive a severe reprimand or punishment
- be getting somewhere — If you say that you are getting somewhere, you mean that you are making progress towards achieving something.
- be in the market for — to wish to buy or acquire
- be shot through with — If something is shot through with an element or feature, it contains a lot of that element or feature.
- beaverhead mountains — a mountain range on the border of E Idaho and SW Montana, in the Bitterroot Range. 10,961 feet (3343 meters).
- belgorod-dnestrovski — a port in SW Ukraine, on the Dniester estuary: belonged to Romania from 1918 until 1940; under Soviet rule (1944–91). Pop: 48 100 (2004 est)
- benavente y martinez — Jacinto. 1866–1954, Spanish dramatist and critic, who wrote over 150 plays. Nobel prize for literature 1922
- benoit b. mandelbrot — Benoit Mandelbrot
- benztropine mesylate — a synthetic anticholinergic, C 21 H 25 NO⋅CH 4 O 3 S, used in the treatment of Parkinson's disease.
- benzyl isoamyl ether — a colorless liquid, C 12 H 18 O, used in soap perfumes.
- bernese mountain dog — a strong sturdy dog of a breed with a bushy tail and a long silky black coat with reddish-brown and white markings, often used as a working farm dog
- best-efforts selling — a method of underwriting a security whereby a syndicate takes a new issue without any guarantees of sale to the issuer.
- bimodal distribution — a frequency distribution with two modes
- biological diversity — Biological diversity is the same as biodiversity.
- bird-footed dinosaur — theropod.
- black-throated diver — a diving bird, Gavia arctica, found in Europe and Asia, and a rare summer visitor to the UK
- blending inheritance — the blending of characteristics of the parents in the offspring, as in a pink flower that results from the mating of a red flower with a white one
- bloodless revolution — the events of 1688–89 by which James II was expelled and the sovereignty conferred on William and Mary.
- blue ridge mountains — a mountain range in the eastern US, extending from West Virginia into Georgia: part of the Appalachian mountains. Highest peak: Mount Mitchell, 2038 m (6684 ft)
- bolometric magnitude — the magnitude of a star derived either from the total energy that it radiates at all wavelengths or from the total energy of those of its wavelengths that are received on earth.
- bomb disposal expert — an expert in bomb disposal
- bone mineral density — a measurement of the amount of calcium and other minerals in a segment of bone, a higher mineral content indicating a higher bone density and strength, used to detect osteoporosis or monitor its treatment.
- born-again christian — person: evangelical
- bottom-up processing — a processing technique, either in the brain or in a computer, in which incoming information is analysed in successive steps and later-stage processing does not affect processing in earlier stages
- boulogne billancourt — a suburb of Paris, in N France.
- boulogne-billancourt — an industrial suburb of SW Paris. Pop: 106 367 (1999)
- bowling on the green — lawn bowling.
- bowling-on-the-green — a game played with wooden balls on a level, closely mowed green having a slight bias, the object being to roll one's ball as near as possible to a smaller white ball at the other end of the green. Also called bowls, bowling on the green. Compare bowl2 (def 2), bowling green, jack1 (def 7), rink (def 5).
- boy-meets-girl story — a film, book, etc whose plot is conventionally or trivially romantic
- brain fingerprinting — a technique in which sensors worn on the head are used to measure the involuntary brain activity of someone in response to certain images or pieces of evidence pertaining to a crime
- breadth-first search — (algorithm) A graph search algorithm which tries all one-step extensions of current paths before trying larger extensions. This requires all current paths to be kept in memory simultaneously, or at least their end points. Opposite of depth-first search. See also best first search.
- breakerless ignition — electronic ignition.
- breakfast and dinner — Breakfast and dinner is a system of accommodations in a hotel or guest house, in which you pay for a room and breakfast and dinner the following day.
- breakfast television — Breakfast television refers to television programmes which are broadcast in the morning at the time when most people are having breakfast.
- bring down the house — to receive enthusiastic applause from the audience