20-letter words containing a, l, f, r
- most general unifier — (logic) If U is the most general unifier of a set of expressions then any other unifier, V, can be expressed as V = UW, where W is another substitution. See also unification.
- mother of the chapel — (in British trade unions in the publishing and printing industries) a woman shop steward
- mother-of-pearl moth — a pyralid moth, Pleuroptya ruralis, having a pale sheen, that is often seen around nettles, on which its green larvae feed
- naturalistic fallacy — the supposed fallacy of inferring evaluative conclusions from purely factual premises
- new zealand fur seal — an Australasian seal, Arctocephalus forsteri
- normal magnification — the magnification produced by a telescope or microscope such that the diameter of the exit pupil of the instrument is equal to the diameter of the pupil of the eye.
- normal zeeman effect — the dividing of a spectral line or lines as a result of placing a radiation source in a magnetic field. The division consists of three equally spaced lines (normal Zeeman effect) in systems for which the spin quantum number is zero, or of three or more unequally spaced lines (anomalous Zeeman effect) in systems for which the spin quantum number is not zero.
- north atlantic drift — an ocean current flowing NE toward the British Isles, formed by the convergence of the Gulf Stream and the Labrador Current SE of Newfoundland.
- northern leaf blight — a disease of corn caused by the fungus Exsherohilum turcicum, characterized by elongate tan-gray elliptical spots with subsequent blighting and necrosis of leaves.
- official secrets act — law: legislation protecting state secret
- olfactory anesthesia — absence or loss of the sense of smell.
- on the factory floor — in a factory; as a factory worker
- order bill of lading — a bill of lading that is issued to the order of a shipper or consignee for delivery of the goods and that can be transferred by endorsement to third parties.
- ousterhout's fallacy — Ousterhout's dichotomy
- paper qualifications — qualifications gained through official examinations, etc, rather than through experience
- 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).
- parametric amplifier — a device, as an electron tube or transistor, that amplifies a high-frequency input signal by sinusoidally varying the reactance of the circuit.
- partial differential — an expression obtained from a given function of several variables by taking the partial derivative with respect to one of the variables and multiplying by the increment in that variable.
- particulars of claim — (in England) the first reading made by the claimant in a county court action, showing the facts upon which he or she relies in support of a claim and the relief asked for
- patent foramen ovale — a congenital heart defect resulting from failure of the foramen ovale to close shortly after birth.
- paternal grandfather — the father of someone's father
- permonosulfuric acid — persulfuric acid (def 1).
- potential difference — voltage
- prefecture apostolic — a territory in the early stage of missionary development.
- probability function — the function the values of which are probabilities of the distinct outcomes of a discrete random variable
- 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.
- refracting telescope — an optical instrument for making distant objects appear larger and therefore nearer. One of the two principal forms (refracting telescope) consists essentially of an objective lens set into one end of a tube and an adjustable eyepiece or combination of lenses set into the other end of a tube that slides into the first and through which the enlarged object is viewed directly; the other form (reflecting telescope) has a concave mirror that gathers light from the object and focuses it into an adjustable eyepiece or combination of lenses through which the reflection of the object is enlarged and viewed. Compare radio telescope.
- 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)
- request for proposal — (programming) (RFP) The publication by a prospective software purchaser of details of the required system in order to attract offers by software developers to supply it. Software development under contract starts with the selection of the software developer by the customer. A request for proposal (also called in Britain an "invitation to tender") is the beginning of the selection process.
- ring wall foundation — A ring wall foundation is a base made of concrete, used to put large tanks on.
- royal air force list — an official list of all serving commissioned officers of the RAF and reserve officers liable for recall
- second earl of essex — 2nd Earl of, Devereux, Robert.
- self-differentiating — to form or mark differently from other such things; distinguish.
- sergeant first class — a noncommissioned officer ranking next above a staff sergeant and below a first or master sergeant.
- small craft advisory — a U.S. National Weather Service advisory of sustained winds, over coastal and inland waters, with speeds of 20–33 knots (23–38 mph, 10–17 m/sec). Regional NWS offices have discretion over the choice of the lower limit.
- snowflake generation — the generation of people who became adults in the 2010s, viewed as being less resilient and more prone to taking offence than previous generations
- snows of kilimanjaro — a short story (1936) by Ernest Hemingway.
- sodium fluoroacetate — a white, amorphous, water-soluble, poisonous powder, C 2 H 2 FO 2 Na, used as a rodenticide.
- software methodology — (programming) The study of how to navigate through each phase of the software process model (determining data, control, or uses hierarchies, partitioning functions, and allocating requirements) and how to represent phase products (structure charts, stimulus-response threads, and state transition diagrams).
- solitary confinement — the confinement of a prisoner in a cell or other place in which he or she is completely isolated from others.
- 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.
- spread like wildfire — If something, especially news or a rumour, spreads like wildfire, it spreads extremely quickly.
- strong nuclear force — an interaction between elementary particles responsible for the forces between nucleons in the nucleus. It operates at distances less than about 10–15 metres, and is about a hundred times more powerful than the electromagnetic interaction
- the legal profession — the profession of law
- the luck of the draw — If you say that something is the luck of the draw, you mean that it is the result of chance and you cannot do anything about it.
- theory of relativity — relativity (def 2).
- there is no call for — If you say that there is no call for someone to behave in a particular way, you are criticizing their behaviour, usually because you think it is rude.