21-letter words containing a, c, o, i
- box-office attraction — something or something that persuades people to buy tickets for a film or play
- breath-of-life packet — (XEROX PARC) An Ethernet packet that contains bootstrap code, periodically sent out from a working computer to infuse the "breath of life" into any computer on the network that has crashed. Computers depending on such packets have sufficient hardware or firmware code to wait for (or request) such a packet during the reboot process. See also dickless workstation. The notional "kiss-of-death packet", with a function complementary to that of a breath-of-life packet, is recommended for dealing with hosts that consume too many network resources. Though "kiss-of-death packet" is usually used in jest, there is at least one documented instance of an Internet subnet with limited address-table slots in a gateway computer in which such packets were routinely used to compete for slots, rather like Christmas shoppers competing for scarce parking spaces.
- 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.
- caroline of brunswick — 1768–1821, wife of George IV of the United Kingdom: tried for adultery (1820)
- 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.
- catalyst-to-oil ratio — The catalyst-to-oil ratio is the amount of a catalyst relative to the amount of oil, which with temperature affects the yield of a process.
- 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 authority — (cryptography, body) (CA or "Trusted Third Party") An entity (typically a company) that issues digital certificates to other entities (organisations or individuals) to allow them to prove their identity to others. A Certificate Authority might be an external company such as VeriSign that offers digital certificate services or they might be an internal organisation such as a corporate MIS department. The Certificate Authority's chief function is to verify the identity of entities and issue digital certificates attesting to that identity. The process uses public key cryptography to create a "network of trust". If I want to prove my identity to you, I ask a CA (who you trust to have verified my identity) to encrypt a hash of my signed key with their private key. Then you can use the CA's public key to decrypt the hash and compare it with a hash you calculate yourself. Hashes are used to decrease the amount of data that needs to be transmitted. The hash function must be cryptographically strong, e.g. MD5.
- 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.
- characteristic vector — a vector for which there exists a scalar such that the value of the vector under a given transformation is equal to the scalar times the vector.
- charge-coupled device — an electronic device, used in imaging and signal processing, in which information is represented as packets of electric charge that are stored in an array of tiny closely spaced capacitors and can be moved from one capacitor to another in a controlled way
- charity commissioners — (in Britain) members of a commission constituted to keep a register of charities and control charitable trusts
- chequebook journalism — Chequebook journalism is the practice of paying people large sums of money for information about crimes or famous people in order to get material for newspaper articles.
- 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
- chink in one's armour — a small but fatal weakness
- chocolate chip cookie — a biscuit containing chips of chocolate
- 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
- civilian review board — a quasi-judicial board of appointed or elected citizens that investigates complaints against the police.
- 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
- clone-and-hack coding — case and paste
- 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
- combination principle — Ritz combination principle.
- comfortably-furnished — containing comfortable furniture
- commercial fertilizer — fertilizer manufactured chemically, as distinguished from natural fertilizer, as manure.
- commercial television — television companies which make money by selling advertising
- commercial translator — (language) An English-like pre-COBOL language for business data processing.
- committal proceedings — a preliminary hearing in a magistrates' court to decide if there is a case to answer
- committing magistrate — a magistrate who decides if there is enough evidence for a case to proceed
- common carotid artery — the part of a carotid artery between its origin and its point of division into branches.
- communication science — the study of ways in which human beings communicate, including speech, gesture, telecommunication systems, publishing and broadcasting media, etc
- communications server — (operating system) IBM's rebranding of ACF.