20-letter words containing a, c, h, r
- polyanthus narcissus — a Eurasian amaryllidaceous plant, Narcissus tazetta, having clusters of small yellow or white fragrant flowers
- post-synchronization — the recording of dialogue and sound effects in synchronization with the picture after the film has been shot.
- potassium bichromate — an orange-red, crystalline, water-soluble, poisonous powder, K 2 Cr 2 O 7 , used chiefly in dyeing, photography, and as a laboratory reagent.
- potassium dichromate — an orange-red crystalline soluble solid substance that is a good oxidizing agent and is used in making chrome pigments and as a bleaching agent. Formula: K2Cr2O7
- powhatan confederacy — a network of Algonquian-speaking Indian settlements in Virginia that was ruled by Powhatan.
- poza rica de hidalgo — a city in N Veracruz, in E Mexico.
- priority inheritance — (parallel) A technique for avoiding priority inversion by temporarily raising the prioriry of all processes that want to access a shared resource to the highest priority level of any of them. Priority inversion occurs where a low priority process, L is holding a resource required by a high priority process, H, but L is not running because a medium priority process, M is running. Under priority inheritance, L temporarily inherits H's priority, allowing L to run and release the resource H is waiting for. For example, an ambulance (H) is stuck behind a lorry (L) waiting at a junction (the shared resource) for a gap in a line of cars (M) using the junction. Applying priority inheritance, the cars give way to the lorry as they would to the ambulance, thus allowing the lorry and then the ambulance to use the junction.
- proactive inhibition — the tendency for earlier memories to interfere with the retrieval of material learned later
- prohibited substance — a substance, such as a drug, etc, that is banned or forbidden by law or other authority
- propylphenyl acetate — phenylpropyl acetate.
- pseudoparenchymatous — (in certain fungi and red algae) a compact mass of tissue, made up of interwoven hyphae or filaments, that superficially resembles plant tissue.
- psychiatric hospital — institution treating mental disorders
- pyroligneous alcohol — methyl alcohol.
- quantum cryptography — a method of coding information based on quantum mechanics, which is said to be unbreakable
- quarantine anchorage — an anchorage for ships awaiting a pratique.
- rachel louise carson — Christopher ("Kit") 1809–68, U.S. frontiersman and scout.
- read the riot act to — to command to stop doing something regarded as wrong, under threat of punishment
- recreational therapy — therapy by means of recreational activities engaged in by the patient
- recreational vehicle — a van or utility vehicle used for recreational purposes, as camping, and often equipped with living facilities. Abbreviation: RV.
- redheaded woodpecker — a North American woodpecker (Melanerpes erythrocephalus), with a bright-red head and neck, black back, and white underparts
- repurchase agreement — a contract between a dealer, as a bank, and an investor, whereby the investor purchases securities with the promise that they will be bought back by the dealer on a designated date, for which the investor receives a fixed return.
- ring-necked pheasant — a gallinaceous Asian bird, Phasianus colchicus, having a white band around its neck, introduced into Great Britain, North America, and the Hawaiian Islands.
- rise to the occasion — to have the courage, wit, etc, to meet the special demands of a situation
- rocky mountain sheep — bighorn.
- sarcastic fringehead — any fish of the genus Neoclinus, characterized by a row of fleshy processes on the head, as N. blanchardi (sarcastic fringehead) of California coastal waters.
- satellite chromosome — a type of densely staining chromosome of uncertain biological function, found in many plant and animal species.
- saxe-weimar-eisenach — a former grand duchy in Thuringia in central Germany.
- scatter site housing — public housing, especially for low-income families, built throughout an urban area rather than being concentrated in a single neighborhood.
- scavenger's daughter — an instrument of torture that doubled over and squeezed the body so strongly and violently that blood was brought forth from the ears and nose: invented in 16th-century England.
- schizoid personality — sb with identity disorder
- schrodinger equation — the wave equation of nonrelativistic quantum mechanics. Also called Schrödinger wave equation. Compare wave equation (def 2).
- schwarzschild radius — the radius at which a gravitationally collapsing celestial body becomes a black hole.
- schwarzschild sphere — the sphere which surrounds a non-rotating uncharged black hole, from within which no information can escape because of gravitational forces
- season ticket holder — a person who has a season ticket
- sellers screw thread — a thread form in a system of standard sizes proposed by Sellers in 1884 and later accepted as standard in the USA, having a 60° flank angle with a flat top and foot
- semiautobiographical — pertaining to or being a fictionalized account of an author's own life.
- sex change operation — a surgical operation designed to change a person's physical sexual characteristics to those of the opposite sex
- short back and sides — If a man has a short back and sides, his hair is cut very short at the back and sides with slightly thicker, longer hair on the top of the head.
- silicon tetrahydride — silane (def 1).
- south american plate — a major tectonic division of the earth's crust, comprising the continent of South America and several ocean basins and bounded on the north by the Caribbean Plate, on the east by the Mid-Atlantic Ridge, on the west by a submarine trench that borders the western coast of the continent, and on the south by the Antarctic Plate.
- southern oscillation — a low-latitude fluctuation of atmospheric pressure closely linked with El Niño events, specifically the periods of El Niño warming and La Niña cooling.
- spanish west african — of or relating to the former Spanish overseas territory of Spanish West Africa (now the overseas provinces of Ifni and Spanish Sahara) or its inhabitants
- spanish-american war — the war between the U.S. and Spain in 1898.
- special relationship — the exceptionally close political, diplomatic, cultural and historical relations between the United States and the United Kingdom
- spherical aberration — variation in focal length of a lens or mirror from center to edge, due to its spherical shape.
- spherical coordinate — Usually, spherical coordinates. any of three coordinates used to locate a point in space by the length of its radius vector and the angles this vector makes with two perpendicular polar planes.
- spiral of archimedes — a curve that is the locus of a point that moves outward with uniform speed along a vector, beginning at the origin, while the vector rotates about the origin with uniform angular velocity. Equation (in polar coordinates): r = aθ.
- splice the mainbrace — to issue and partake of an extra allocation of alcoholic spirits
- st. george's channel — a channel between Wales and Ireland, connecting the Irish Sea and the Atlantic. 100 miles (160 km) long; 50–90 miles (81–145 km) wide.
- stallman, richard m. — Richard Stallman