18-letter words containing r, e, n, t, o
- cesarean (section) — a surgical operation for delivering a baby by cutting through the mother's abdominal and uterine walls
- character encoding — (character) (Or "character encoding scheme") A mapping between binary data values and character code positions (or "code points"). Early systems stored characters in a variety of ways, e.g. four six-bit characters in a 24-bit word, but around 1960, eight-bit bytes started to become the most common data storage layout, with each character stored in one byte, typically in the ASCII character set. In the case of ASCII, the character encoding is an identity mapping: code position 65 maps to the byte value 65. This is possible because ASCII uses only code positions representable as single bytes, i.e., values between 0 and 255. (US-ASCII only uses values 0 to 127, in fact.) From the late 1990s, there was increased use of larger character sets such as Unicode and many CJK coded character sets. These can represent characters from many languages and more symbols.
- charge conjugation — the mathematical operation of replacing every elementary particle by its antiparticle. Symbol: C.
- check verification — Check verification is a system that checks national databases of information about individuals to make sure that checks will be honored and fraud is not being committed.
- checkpoint charlie — a crossing between East and West Berlin during the Cold War
- chinese revolution — the overthrow of the last Manchu emperor and the establishment of a republic in China (1911–12)
- chinese watermelon — a tropical Asian vine, Benincasa hispida, of the gourd family, having a brown, hairy stem, large, solitary, yellow flowers, and white, melonlike fruit.
- chloroacetophenone — a white, crystalline, water-insoluble, poisonous solid, C 8 H 7 ClO, used in solution as a tear gas. Abbreviation: CN.
- chlorobromomethane — a clear, colorless, volatile, nonflammable liquid, CH 2 ClBr, used chiefly as an extinguishing agent in fire extinguishers and as a solvent in organic synthesis.
- chrétien de troyes — 12th century, French poet, who wrote the five Arthurian romances Erec; Cligès; Lancelot, le chevalier de la charette; Yvain, le chevalier au lion; and Perceval, le conte del Graal (?1155–?1190), the first courtly romances
- christian brothers — a religious congregation of laymen founded in France in 1684 for the education of the poor
- christian democrat — a member or supporter of a Christian Democratic party
- christian endeavor — an organization of young people of various evangelical Protestant churches, formed in 1881 to promote Christian principles and service.
- christian reformed — of or relating to a Protestant denomination (Christian Reformed Church) organized in the U.S. in 1857 by groups that had seceded from the Dutch Reformed Church.
- chromatic semitone — the pitch difference between one note and its sharpened or flattened equivalent
- cigar-store indian — a wooden statue of an American Indian, traditionally displayed at the entrance of cigar stores.
- citizen journalism — the involvement of non-professionals in reporting news, esp in blogs and other websites
- cleopatra's needle — either of two Egyptian obelisks, originally set up at Heliopolis about 1500 bc: one was moved to the Thames Embankment, London, in 1878, the other to Central Park, New York, in 1880
- closed corporation — a corporation the stock of which is owned by a small number of persons and is rarely traded on the open market
- coast rhododendron — a rhododendron, Rhododendron macrophyllum, of western North America, having large clusters of rose-purple flowers spotted with brown: the state flower of Washington.
- coitus interruptus — the deliberate withdrawal of the penis from the vagina before ejaculation
- collection charges — the charges levied to cover expenses for the collection of debt
- collision diameter — the distance between the centers of two colliding molecules when at their closest point of approach.
- color transparency — a positive color image photographically produced on transparent film or glass and viewed by transmitted light, usually by projection.
- colour commentator — a sports celebrity who works as part of a commentary team
- combination square — an adjustable device for carpenters, used as a try square, miter square, level, etc.
- combined operation — a military operation carried out jointly by allied forces
- combustion chamber — an enclosed space in which combustion takes place, such as the space above the piston in the cylinder head of an internal-combustion engine or the chambers in a gas turbine or rocket engine in which fuel and oxidant burn
- combustion furnace — a furnace used in the laboratory to carry out elemental analysis of organic compounds
- come the raw prawn — to attempt deception
- commando operation — a major operation for treatment of cancer of the head and neck, involving removal of many facial structures and subsequent surgical reconstruction
- common denominator — In mathematics, a common denominator is a number which can be divided exactly by all the denominators in a group of fractions.
- common wintergreen — a plant (Pyrola minor) of temperate and arctic regions, having rounded leaves and small pink globose flowers: family Pyrolaceae
- community property — the joint ownership of the property of a husband and wife
- compartmentalizing — Present participle of compartmentalize.
- compensation award — an amount of money awarded as compensation in a court case
- compensation order — (in Britain) the requirement of a court that an offender pay compensation for injury, loss, or damage resulting from an offence, either in preference to or as well as a fine
- complementarianism — The doctrine that genders in a society should have complementary roles.
- complementary base — either of the nucleotide bases linked by a hydrogen bond on opposite strands of DNA or double-stranded RNA: guanine is the complementary base of cytosine, and adenine is the complementary base of thymine in DNA and of uracil in RNA.
- complementary gene — one of a pair of genes, each from different loci, that together are required for the expression of a certain characteristic
- composition rubber — manufactured rubber
- composition series — a normal series of subgroups in which no additional subgroups can be inserted.
- compression stroke — The compression stroke is the stroke in an engine in which the air or air/fuel mixture is compressed before ignition.
- compressor station — A compressor station is a facility with several compressors (= devices that increase the pressure of air or natural gas) and other equipment to pump natural gas under pressure over long distances.
- computer animation — animated film or video that is generated by computers
- computer scientist — a person with advanced knowledge of computers and how they work
- computer telephony — Computer Telephone Integration
- computer-generated — produced by a computer program
- concentration camp — A concentration camp is a prison in which large numbers of ordinary people are kept in very bad conditions, usually during a war.
- concentration cell — a galvanic cell consisting of two electrodes of the same metal each in different concentrations of a solution of the same salt of that metal.