17-letter words containing a, i, r, o, u, t
- munitions factory — a factory where munitions are made
- nasolacrimal duct — a membranous canal extending from the lacrimal sac to the nasal cavity, through which tears are discharged into the nose.
- national security — defence of a country
- natural deduction — (logic) A set of rules expressing how valid proofs may be constructed in predicate logic. In the traditional notation, a horizontal line separates premises (above) from conclusions (below). Vertical ellipsis (dots) stand for a series of applications of the rules. "T" is the constant "true" and "F" is the constant "false" (sometimes written with a LaTeX \perp). "^" is the AND (conjunction) operator, "v" is the inclusive OR (disjunction) operator and "/" is NOT (negation or complement, normally written with a LaTeX \neg). P, Q, P1, P2, etc. stand for propositions such as "Socrates was a man". P[x] is a proposition possibly containing instances of the variable x, e.g. "x can fly". A proof (a sequence of applications of the rules) may be enclosed in a box. A boxed proof produces conclusions that are only valid given the assumptions made inside the box, however, the proof demonstrates certain relationships which are valid outside the box. For example, the box below labelled "Implication introduction" starts by assuming P, which need not be a true proposition so long as it can be used to derive Q. Truth introduction: - T (Truth is free). Binary AND introduction: ----------- | . | . | | . | . | | Q1 | Q2 | ----------- Q1 ^ Q2 (If we can derive both Q1 and Q2 then Q1^Q2 is true). N-ary AND introduction: ---------------- | . | .. | . | | . | .. | . | | Q1 | .. | Qn | ---------------- Q1^..^Qi^..^Qn Other n-ary rules follow the binary versions similarly. Quantified AND introduction: --------- | x . | | . | | Q[x] | --------- For all x . Q[x] (If we can prove Q for arbitrary x then Q is true for all x). Falsity elimination: F - Q (Falsity opens the floodgates). OR elimination: P1 v P2 ----------- | P1 | P2 | | . | . | | . | . | | Q | Q | ----------- Q (Given P1 v P2, if Q follows from both then Q is true). Exists elimination: Exists x . P[x] ----------- | x P[x] | | . | | . | | Q | ----------- Q (If Q follows from P[x] for arbitrary x and such an x exists then Q is true). OR introduction 1: P1 ------- P1 v P2 (If P1 is true then P1 OR anything is true). OR introduction 2: P2 ------- P1 v P2 (If P2 is true then anything OR P2 is true). Similar symmetries apply to ^ rules. Exists introduction: P[a] ------------- Exists x.P[x] (If P is true for "a" then it is true for all x). AND elimination 1: P1 ^ P2 ------- P1 (If P1 and P2 are true then P1 is true). For all elimination: For all x . P[x] ---------------- P[a] (If P is true for all x then it is true for "a"). For all implication introduction: ----------- | x P[x] | | . | | . | | Q[x] | ----------- For all x . P[x] -> Q[x] (If Q follows from P for arbitrary x then Q follows from P for all x). Implication introduction: ----- | P | | . | | . | | Q | ----- P -> Q (If Q follows from P then P implies Q). NOT introduction: ----- | P | | . | | . | | F | ----- / P (If falsity follows from P then P is false). NOT-NOT: //P --- P (If it is not the case that P is not true then P is true). For all implies exists: P[a] For all x . P[x] -> Q[x] ------------------------------- Q[a] (If P is true for given "a" and P implies Q for all x then Q is true for a). Implication elimination, modus ponens: P P -> Q ---------- Q (If P and P implies Q then Q). NOT elimination, contradiction: P /P ------ F (If P is true and P is not true then false is true).
- natural harmonics — harmonics of a note produced on a stringed instrument by lightly touching an open or unstopped sounded string.
- natural logarithm — a logarithm having e as a base. Symbol: ln.
- natural selection — the process by which forms of life having traits that better enable them to adapt to specific environmental pressures, as predators, changes in climate, or competition for food or mates, will tend to survive and reproduce in greater numbers than others of their kind, thus ensuring the perpetuation of those favorable traits in succeeding generations.
- neurodegenerative — Resulting in or characterized by degeneration of the nervous system, especially the neurons in the brain.
- neurofibromatosis — a dominantly inherited genetic disorder characterized by flat brown patches on the skin, neurofibromas of the skin and internal organs, and in some cases skeletal deformity.
- neuropathological — (medicine) Of, pertaining to, or arising from neuropathology, the pathology of nerve tissue.
- neuropsychiatrist — A medical doctor specializing in neuropsychiatry; a medical doctor dealing with disorders that have both neurological and psychiatric features.
- neurotransmission — the transmission of a nerve impulse across a synapse.
- neurotransmissive — Relating to neurotransmission.
- neurotransmitters — Plural form of neurotransmitter.
- non-argumentative — fond of or given to argument and dispute; disputatious; contentious: The law students were an unusually argumentative group.
- non-authoritarian — favoring complete obedience or subjection to authority as opposed to individual freedom: authoritarian principles; authoritarian attitudes.
- non-authoritative — having due authority; having the sanction or weight of authority: an authoritative opinion.
- non-instructional — the act or practice of instructing or teaching; education.
- non-subordination — the act of placing in a lower rank or position: The refusal to allow women to be educated was part of society's subordination of women to men.
- norwegian current — an ocean current formed from the terminus of the North Atlantic Current, flowing N along the Norwegian coast into the Barents Sea.
- nuclear radiation — Physics. radiation in the form of elementary particles emitted by an atomic nucleus, as alpha rays or gamma rays, produced by decay of radioactive substances or by nuclear fission.
- numerical control — control of a machine tool, or other device used in a manufacturing process, by a computer, other control circuitry, or recorded digital commands.
- nursery education — education provided at a school for young children, usually from three to five years old
- odds-on favourite — a person, team, horse, etc that is regarded as the most likely to win a competition
- odour of sanctity — sanctimoniousness
- old south arabian — a group of four closely related Semitic languages, having a writing system and used from about the eighth to the fifth centuries b.c. in the southern part of Arabia.
- opening arguments — the statements or arguments provided by lawyers at the beginning of a trial
- opportunistically — adhering to a policy of opportunism; practicing opportunism.
- organ-pipe cactus — a treelike or columnar cactus, Lemaireocereus marginatus, of Mexico, having a central, erect spine surrounded by spreading spines in clusters of five to eight, and funnel-shaped, brownish-purple flowers.
- osculating circle — circle of curvature.
- outline agreement — a contract, etc, setting out the preliminary terms or guidelines for an agreement; a preliminary agreement
- outside broadcast — An outside broadcast is a radio or television programme that is not recorded or filmed in a studio, but in another building or in the open air.
- palace revolution — a challenge to or overthrow of a sovereign or other leader by members of the ruling family or group.
- particularization — to make particular.
- per procurationem — by one acting as an agent; by proxy.
- perforation gauge — a marked ruler used to measure the number of perforations per unit length along the borders of a stamp.
- permutation group — a mathematical group whose elements are permutations and in which the product of two permutations is the same permutation as is obtained by performing them in succession.
- personal equation — the tendency to personal bias that accounts for variation in interpretation or approach and for which allowance must be made.
- phototherapeutics — the branch of therapeutics that deals with the curative use of light rays.
- pinpoint accuracy — extreme accuracy
- point of purchase — designating or in use at a retail outlet where an item can be purchased; point-of-sale: point-of-purchase displays to entice the buyer.
- point-of-purchase — designating or in use at a retail outlet where an item can be purchased; point-of-sale: point-of-purchase displays to entice the buyer.
- political refugee — a person who has fled from a homeland because of political persecution.
- polyvinyl butyral — a white, water-insoluble, polyvinyl acetal made with butyraldehyde, used chiefly as an interlayer in the manufacture of safety glass.
- portuguese guinea — former name of Guinea-Bissau.
- poststructuralism — a variation of structuralism, often seen as a critique, emphasizing plurality of meaning and instability of concepts that structuralism uses to define society, language, etc.
- postural drainage — a therapy for clearing congested lungs by placing the patient in a position for drainage by gravity, often accompanied by percussion with hollowed hands.
- potassium bromate — a white, crystalline, water-soluble powder, KBrO 3 , used chiefly as an oxidizing agent and as an analytical reagent.
- potassium bromide — a white, crystalline, water-soluble powder, KBr, having a bitter saline taste: used chiefly in the manufacture of photographic papers and plates, in engraving, and in medicine as a sedative.
- potassium nitrate — a crystalline compound, KNO 3 , produced by nitrification in soil, and used in gunpowders, fertilizers, and preservatives; saltpeter; niter.