21-letter words containing a, c, t, i, o, n
- atmospheric-inversion — an act or instance of inverting.
- atomic disintegration — a process resulting in the change of a radioactive nucleus, either by emission of an alpha, beta, or gamma ray or by fission, and producing a change in the original mass, atomic number, or energy
- atomic unit of length — (in the Bohr atom) the radius of the electron orbit having the lowest energy.
- atrioventricular node — a small mass of muscular fibers at the base of the wall between the atria, conducting impulses received from the sinoatrial node by way of the atrioventricular bundles and, under certain conditions, functioning for the sinoatrial node as pacemaker of the heart. Abbreviation: A-V node.
- australian cattle dog — a compact strongly-built dog of a breed with pricked ears and a smooth bluish-grey coat, often used for controlling and moving cattle
- automatic hyphenation — (text) A feature of some word processors which can insert hyphens into words which would otherwise extend beyond the right hand margin of the page. More advanced word processors may have options to control the position of the hyphen, to restrict certain words from being hyphenated, and to allow custom dictionaries of hyphenation points to be built up.
- aversive conditioning — a type of behavior conditioning in which noxious stimuli are associated with undesirable or unwanted behavior that is to be modified or abolished, as the use of nausea-inducing drugs in the treatment of alcoholism.
- axiom of countability — the property satisfied by a topological space in which the neighborhood system of each point has a base consisting of a countable number of neighborhoods (first axiom of countability) or the property satisfied by a topological space that has a base for its topology consisting of a countable number of subsets of the space (second axiom of countability)
- background projection — the projection from the rear of previously photographed material on a translucent screen, used as background for a television or motion-picture shot.
- bad conduct discharge — a discharge of a person from military service for an offense less serious than one for which a dishonorable discharge is given.
- baja california norte — a state of NW Mexico, in the N part of the Lower California peninsula. Capital: Mexicali. Pop: 2 487 700 (2000). Area: about 71 500 sq km (27 600 sq miles)
- ball-and-socket joint — a coupling between two rods, tubes, etc, that consists of a spherical part fitting into a spherical socket, allowing free movement within a specific conical volume
- banach-tarski paradox — (mathematics) It is possible to cut a solid ball into finitely many pieces (actually about half a dozen), and then put the pieces together again to get two solid balls, each the same size as the original. This paradox is a consequence of the Axiom of Choice.
- barrier contraceptive — any form of contraceptive that prevents impregnation by physically preventing the sperm from reaching the egg
- basis of articulation — a configuration of the speech tract that represents the most neutral articulatory configuration for a given language.
- baudouin de courtenay — Jan Ignacy Niecisław [yahn ig-nah-tsi nye-tsis-lahf] /yɑn ɪgˈnɑ tsɪ ˈnyɛ tsɪsˌlɑf/ (Show IPA), 1845–1929, Polish linguist: pioneer in modern phonology.
- behavior modification — a technique that seeks to modify animal and human behavior through application of the principles of conditioning, in which rewards and reinforcements, or punishments, are used to establish desired habits, or patterns of behavior
- behavioural contagion — the spread of a particular type of behaviour, such as crying, through a crowd or group of people
- bibliographic control — the identification, description, analysis, and classification of books and other materials of communication so that they may be effectively organized, stored, retrieved, and used when needed.
- binomial nomenclature — a system for naming plants and animals by means of two Latin names: the first indicating the genus and the second the species to which the organism belongs, as in Panthera leo (the lion)
- boiling-water reactor — a nuclear reactor using water as coolant and moderator, steam being produced in the reactor itself: enriched uranium oxide cased in zirconium is the fuel
- box-office attraction — something or something that persuades people to buy tickets for a film or play
- british north america — (formerly) Canada or its constituent regions or provinces that formed part of the British Empire
- burroughs corporation — (company) A company which merged with Sperry Univac to form Unisys Corporation. They produced the Datatron 200 series among other computers.
- cancellation deadline — A cancellation deadline is a date before which you must cancel a hotel reservation without paying any money.
- canticle of canticles — another name for the Song of Solomon, used in the Douay Bible
- cantilever foundation — a building foundation supporting its load partly or wholly upon cantilevers.
- cartesian coordinates — a system of representing points in space in terms of their distance from a given origin measured along a set of mutually perpendicular axes. Written (x,y,z) with reference to three axes
- casing collar locator — A casing collar locator is a tool that is placed down the borehole to allow depths to be measured by detecting the position of the casing collar.
- cat on a hot tin roof — a play (1955) by Tennessee Williams.
- category merchandiser — A category merchandiser is a person whose job is to maintain stocks, manage displays and promote sales of a certain product category such as footwear.
- catherine of braganza — 1638–1705, wife of Charles II of England, daughter of John IV of Portugal
- caviar to the general — a thing appealing only to a highly cultivated taste: Hamlet II, ii
- central european time — the standard time adopted by Western European countries one hour ahead of Greenwich Mean Time, corresponding to British Summer Time
- central limit theorem — any of several theorems stating that the sum of a number of random variables obeying certain conditions will assume a normal distribution as the number of variables becomes large.
- certificate of origin — a document stating the name of the country that produced a specified shipment of goods: often required before importation of goods
- character recognition — Character recognition is a process which allows computers to recognize written or printed characters such as numbers or letters and to change them into a form that the computer can use.
- charity commissioners — (in Britain) members of a commission constituted to keep a register of charities and control charitable trusts
- chief warrant officer — a senior-ranking warrant officer in various armed forces
- chinese water torture — a form of torture in which water is made to drip for a long period of time onto a victim's forehead to drive him insane
- christmas decorations — decorations of different kinds appropriate to Christmas, such as tinsel, candles, images of angels, etc.
- circle of declination — hour circle.
- circular polarization — electromagnetic radiation (esp light) in which the electric field vector describes a circle about the direction of propagation at any point in the path of the radiation
- class-relation method — (programming) A design technique based on the concepts of object-oriented programming and the Entity-Relationship model from the French company Softeam.
- clayton antitrust act — an act of Congress in 1914 supplementing the Sherman Antitrust Act and establishing the FTC.
- clement of alexandria — Saint. original name Titus Flavius Clemens. ?150–?215 ad, Greek Christian theologian: head of the catechetical school at Alexandria; teacher of Origen. Feast day: Dec 5
- clinical psychologist — a practitioner of clinical psychology
- collective bargaining — When a trade union engages in collective bargaining, it has talks with an employer about its members' pay and working conditions.
- collimator viewfinder — a type of viewfinder in a camera
- collins street farmer — a businessman who invests in farms, land, etc