18-letter words containing r, i, o
- chord of the sixth — sixth chord.
- 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.
- christopher sholes — Christopher Latham [ley-thuh m,, -th uh m] /ˈleɪ θəm,, -ðəm/ (Show IPA), 1819–90, U.S. inventor of the typewriter.
- chromatic printing — printing from blocks or types inked with various colours
- chromatic semitone — the pitch difference between one note and its sharpened or flattened equivalent
- chromolithographer — One engaged in chromolithography.
- chromolithographic — Pertaining to, or made by, chromolithography.
- chronic alcoholism — long-term alcohol addiction
- 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.
- circular dichroism — selective absorption of one of the two possible circular polarizations of light.
- circulatory system — the system concerned with the transport of blood and lymph, consisting of the heart, blood vessels, lymph vessels, etc
- circumnavigational — Relating to circumnavigation.
- citizen journalism — the involvement of non-professionals in reporting news, esp in blogs and other websites
- claustrophobically — In a claustrophobic way.
- clay-colored robin — any of several small Old World birds having a red or reddish breast, especially Erithacus rubecula, of Europe.
- clobbering machine — pressure to conform with accepted standards
- 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 scholarship — a scholarship for which only certain people, such as those from a particular school or with a particular surname, are eligible
- closure conversion — (theory) The transformation of continuation passing style code so that the only free variables of functions are names of other functions. See also Lambda lifting.
- 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 coverage — Collision coverage is insurance cover for vehicle accidents.
- collision diameter — the distance between the centers of two colliding molecules when at their closest point of approach.
- colonic irrigation — Colonic irrigation is a medical procedure in which a person's colon is washed by injecting water or other fluids into it.
- comb-footed spider — any of numerous spiders constituting the family Theridiidae, having a comblike row of bristles on the tarsi of the hind legs.
- 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 to grips with — If you come to grips with a problem, you consider it seriously, and start taking action to deal with it.
- come to terms with — If you come to terms with something difficult or unpleasant, you learn to accept and deal with it.
- commander in chief — Also, Commander in Chief. the supreme commander of the armed forces of a nation or, sometimes, of several allied nations: The president is the Commander in Chief of the U.S. Army, Navy, and Air Force.
- commander-in-chief — A commander-in-chief is a senior officer who is in charge of all the forces in a particular area.
- commanding officer — A commanding officer is an officer who is in charge of a military unit.
- commando operation — a major operation for treatment of cancer of the head and neck, involving removal of many facial structures and subsequent surgical reconstruction
- commedia dell'arte — a form of popular comedy developed in Italy during the 16th to 18th centuries, with stock characters such as Punchinello, Harlequin, and Columbine, in situations improvised from a plot outline
- commercial attache — an attaché in an embassy or legation representing the commercial interests of his or her country.
- commercial college — a college providing tuition in commercial skills, such as shorthand and book-keeping
- commercial vehicle — a vehicle for carrying goods or (less commonly) passengers
- 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