20-letter words containing a, u, d, i
- officer of the guard — an officer, acting under the officer of the day, who is responsible for the instruction, discipline, and performance of duty of the guard in a post, camp, or station. Abbreviation: OG, O.G.
- pappus of alexandria — 3rd century bc, Greek mathematician, whose eight-volume Synagoge is a valuable source of information about Greek mathematics
- parallel of altitude — almucantar.
- parallel of latitude — parallel (def 9).
- pedal steel (guitar) — a steel guitar mounted on legs and equipped with pedals that serve as an additional means of changing pitch
- pentobarbital sodium — a barbiturate drug used in medicine as a sedative and hypnotic. Formula: C11H17N2O3Na
- pentose nucleic acid — a nucleic acid containing a pentose.
- permonosulfuric acid — persulfuric acid (def 1).
- peroxysulphuric acid — a white hygroscopic crystalline unstable oxidizing acid. Formula: H2SO5
- perpendicular gothic — the style of Gothic architecture in England during the 14th and 15th centuries, characterized by tracery having vertical lines, a four-centred arch, and fan vaulting
- physical double star — two stars that appear as one if not viewed through a telescope with adequate magnification, such as two stars that are separated by a great distance but are nearly in line with each other and an observer (optical double star) or those that are relatively close together and comprise a single physical system (physical double star)
- physiologic jaundice — a transitory jaundice that affects some infants for the first few days after birth.
- 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
- pound cost averaging — a method of accumulating capital by investing a fixed sum in a particular security at regular intervals, in order to achieve an average purchase price below the arithmetic average of the market prices on the purchase dates
- prince william sound — a sound in the Gulf of Alaska, on the S coast of Alaska: S end of Trans-Alaska oil pipeline at port of Valdez.
- production agreement — a contract concerning the production or manufacture of something
- prohibited substance — a substance, such as a drug, etc, that is banned or forbidden by law or other authority
- pseudo-psychological — of or relating to psychology.
- public administrator — an official of a city, county, or state government.
- qualitative identity — the relation that holds between two relata that have properties in common. This term is used to distinguish many uses of the words identical or same in ordinary language from strict identity or numerical identity
- quantum bogodynamics — /kwon'tm boh"goh-di:-nam"iks/ A theory that characterises the universe in terms of bogon sources (such as politicians, used-car salesmen, TV evangelists, and suits in general), bogon sinks (such as taxpayers and computers), and bogosity potential fields. Bogon absorption causes human beings to behave mindlessly and machines to fail (and may also cause both to emit secondary bogons); however, the precise mechanics of bogon-computron interaction are not yet understood. Quantum bogodynamics is most often invoked to explain the sharp increase in hardware and software failures in the presence of suits; the latter emit bogons, which the former absorb.
- quantum field theory — any theory in which fields are treated by the methods of quantum mechanics; each field can then be regarded as consisting of particles of a particular kind, which may be created and annihilated.
- queen elizabeth land — an area of British Antarctic Territory, situated south of Weddell Sea and between longitudes 20°W and 80°W, stretching from Filchner-Ronne Ice Shelf to the South Pole. Area: 437 000 sq km (169 000 sq miles)
- radial triangulation — triangulation based upon lines radiating from the center of each of two overlapping photographs to certain objects appearing on each photograph.
- reductio ad absurdum — a reduction to an absurdity; the refutation of a proposition by demonstrating the inevitably absurd conclusion to which it would logically lead.
- refuse disposal unit — a unit or part of a sink that disposes of waste food, etc, by grinding
- republic of maldives — a republic occupying an archipelago of 1087 coral islands in the Indian Ocean, southwest of Sri Lanka: came under British protection in 1887; became independent in 1965 and a republic in 1968; member of the Commonwealth (1982–2016). The economy and infrastructure were severely damaged in the Indian Ocean tsunami of December 2004. Official language: Divehi. Official religion: (Sunni) Muslim. Currency: rufiyaa. Capital: Malé. Pop: 393 988 (2013 est). Area: 298 sq km (115 sq miles)
- rheumatoid arthritis — a chronic autoimmune disease characterized by inflammation of the joints, frequently accompanied by marked deformities, and ordinarily associated with manifestations of a general, or systemic, affliction.
- ring wall foundation — A ring wall foundation is a base made of concrete, used to put large tanks on.
- rough-winged swallow — either of two New World swallows of the genus Stelgidopteryx, having outer primary feathers with small barblike hooks on the margins.
- 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.
- secure accommodation — an institution where young offenders are kept in custody
- serious fraud office — a UK government office responsible for investigating and prosecuting serious fraud cases
- serra da mantiqueira — a mountain range in SE Brazil, running parallel to the coast. Highest point, 9140 feet (2785 meters).
- shareholders' equity — Shareholders' equity is the total amount of ownership investment in a company.
- shoulder-length hair — hair that reaches a person's shoulders
- sierra madre del sur — a plateau mountain range in Guerrero and Oaxaca states, S Mexico. Highest peak 12,149 feet (3703 meters).
- social security card — a card that contains details of a person's social security number
- sodium fluoroacetate — a white, amorphous, water-soluble, poisonous powder, C 2 H 2 FO 2 Na, used as a rodenticide.
- sodium meta-arsenite — sodium arsenite.
- sodium metabisulfite — Sodium metabisulfite is a crystalline compound used as an antioxidant.
- sound-and-light show — a nighttime spectacle or performance, at which a building, historic site, etc., is illuminated and the historic significance is imparted to spectators by means of narration, sound effects, and music.
- south orkney islands — an uninhabited group of islands in the S Atlantic, southeast of Cape Horn: formerly a dependency of the Falkland Islands; part of the British Antarctic Territory since 1962 (claims are suspended under the Antarctic Treaty). Area: 621 sq km (240 sq miles)
- specific conductance — conductivity (def 2).
- specific-conductance — conductivity (def 2).
- subjective idea-list — a doctrine that the world has no existence independent of sensations or ideas.
- suitland-silver hill — a city in central Maryland, near Washington, D.C.
- summary jurisdiction — the right a court has to adjudicate immediately upon some matter arising during its proceedings
- sunday-go-to-meeting — most presentable; best: Sunday-go-to-meeting clothes.