18-letter words containing i, s, o, t, n
- castration complex — an unconscious fear of having one's genitals removed, as a punishment for wishing to have sex with a parent
- catalogue raisonne — a descriptive catalogue, esp one covering works of art in an exhibition or collection
- catalonian jasmine — a shrub, Jasminum grandiflorum, of India, having crimson-tinged, fragrant white flowers, grown as an ornamental and for perfume.
- catherine of siena — Saint. 1347–80, Italian mystic and ascetic; patron saint of the Dominican order. Feast day: April 29
- catskill mountains — a mountain range in SE New York State: resort. Highest peak: Slide Mountain, 1261 m (4204 ft)
- caucasus mountains — a mountain range in SW Russia, running along the N borders of Georgia and Azerbaijan, between the Black Sea and the Caspian Sea: mostly over 2700 m (9000 ft). Highest peak: Mount Elbrus, 5642 m (18 510 ft)
- centralized school — a public school formed from the pupils and teachers of a number of discontinued smaller schools, especially in a rural district.
- cesarean (section) — a surgical operation for delivering a baby by cutting through the mother's abdominal and uterine walls
- championship point — a point that would decide the winner of a match that would decide the championship
- chebyshev equation — Tchebycheff equation.
- 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.
- 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.
- christmas shopping — shopping especially for Christmas presents, but also for Christmas food and drink, and all the other things required over the Christmas period.
- christmas stocking — A Christmas stocking is a long sock which children hang up on Christmas Eve. During the night, parents fill the stocking with small presents.
- chromatic semitone — the pitch difference between one note and its sharpened or flattened equivalent
- chronic bronchitis — persistent respiratory disease
- chronostratigraphy — The branch of geology concerned with establishing the absolute ages of strata.
- 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
- classified section — the part of a publication that contains classified advertising
- closed corporation — a corporation the stock of which is owned by a small number of persons and is rarely traded on the open market
- closed-box testing — functional testing
- coastguard station — the headquarters or local offices of a coastguard
- 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.
- colloidal solution — a mixture having particles of one component, with diameters between 10 −7 and 10 −9 metres, suspended in a continuous phase of another component. The mixture has properties between those of a solution and a fine suspension
- combination square — an adjustable device for carpenters, used as a try square, miter square, level, etc.
- 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
- community hospital — (in the US) a local hospital
- compassion fatigue — the inability to react sympathetically to a crisis, disaster, etc, because of overexposure to previous crises, disasters, etc
- 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
- compensation point — the concentration of atmospheric carbon dioxide at which the rate of carbon dioxide uptake by a photosynthesizing plant is exactly balanced by its rate of carbon dioxide release in respiration and photorespiration
- complementarianism — The doctrine that genders in a society should have complementary roles.
- composite function — a function obtained from two given functions, where the range of one function is contained in the domain of the second function, by assigning to an element in the domain of the first function that element in the range of the second function whose inverse image is the image of the element.
- 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 scientist — a person with advanced knowledge of computers and how they work
- concentration span — the length of time a person can concentrate on something
- conceptual realism — the doctrine that universals have real and independent existence.
- conceptualisations — Plural form of conceptualisation.