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17-letter words containing a, t, o, n

  • nasolacrimal duct — a membranous canal extending from the lacrimal sac to the nasal cavity, through which tears are discharged into the nose.
  • national assembly — the body constituted by the French Third Estate in June 1789 after the calling of the Estates General. It was dissolved in Sept 1791 to be replaced by the new Legislative Assembly
  • national cemetery — a cemetery, maintained by the U.S. government, for persons who have served honorably in the armed forces.
  • national covenant — an agreement (1638) among Scottish Presbyterians to uphold their faith in Scotland.
  • national heritage — country's cultural legacy
  • national identity — characteristics of a given nationality
  • national monument — a monument, as a historic site or geographical area, owned and maintained in the public interest by the federal government.
  • national seashore — an area of seacoast set aside and maintained by the U.S. government for purposes of recreation or wildlife study.
  • national security — defence of a country
  • nationalist china — China, Republic of.
  • nationalistically — In a nationalistic manner.
  • 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 resources — a naturally occurring source of wealth, as land or water.
  • 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.
  • natural-resources — a naturally occurring source of wealth, as land or water.
  • naval air station — military airbase for the navy
  • naval observatory — an astronomical observatory located in Washington, D.C., operated by the U.S. government, and responsible for the U.S. time service.
  • navigation lights — lights on an aircraft
  • navigation system — A navigation system is an instrument that determines the position of a vehicle and the route to a particular place.
  • near-earth object — a comet or asteroid pushed by the gravitational attraction of nearby planets into an orbit that allows it to enter the earth's orbit and thereby pose a danger of collision. Abbreviation: NEO.
  • neath port talbot — a county borough in S Wales, created from part of West Glamorgan in 1996. Administrative centre: Port Talbot. Pop: 135 300 (2003 est). Area: 439 sq km (169 sq miles)
  • negative polarity — the grammatical character of a word or phrase, such as ever or any, that may normally be used only in a semantically or syntactically negative or interrogative context
  • negative theology — a theological approach or tradition in which the nature of God is thought to be unknowable and is only understood through negative statements. See also apophasis (def 2).
  • negotiating table — If you say that people are at the negotiating table, you mean that they are having discussions in order to settle a dispute or reach an agreement.
  • neo-malthusianism — a view or doctrine advocating population control, especially by contraception.
  • neo-scholasticism — a contemporary application of Scholasticism to modern problems and life.
  • nephelometrically — By means of nephelometry.
  • network marketing — a marketing strategy in which sales representatives of a company recruit other salespeople and earn commissions on their own sales and on the sales made by their team: Use your personal relationships to be successful in network marketing.
  • 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.
  • new orleans style — a style of jazz developed in New Orleans early in the 20th century, influenced by blues, ragtime, marching band music, and minstrelsy and marked by polyphonic group improvisation.
  • new scotland yard — See under Scotland Yard (def 1).
  • newfoundland time — a form of civil time observed on the island of Newfoundland, one and one-half hours later than Eastern time and a half hour later than Atlantic time.
  • ngaliema mountain — Mount, a mountain with two summits, in central Africa, between Uganda and the Democratic Republic of the Congo: highest peak in the Ruwenzori group. 16,790 feet (5119 meters).
  • ninety-day wonder — an officer commissioned in a branch of the armed forces after an unusually short training period, especially after a three-months officers' training course during World War II.
  • ninth commandment — “Thou shalt not bear false witness against thy neighbor”: ninth of the Ten Commandments.
  • nitrogen fixation — any process of combining atmospheric nitrogen with other elements, either by chemical means or by bacterial action: used chiefly in the preparation of fertilizers, industrial products, etc.
  • nitrogen narcosis — a semistupor, lightheadedness, or euphoria experienced by deep-sea divers when nitrogen from air enters the blood at higher than atmospheric pressure.
  • nitroxanthic acid — picric acid.
  • non-accommodation — the act of accommodating; state or process of being accommodated; adaptation.
  • non-argumentative — fond of or given to argument and dispute; disputatious; contentious: The law students were an unusually argumentative group.
  • non-assignability — capable of being specified: The word has no assignable meaning in our language.
  • non-authoritarian — favoring complete obedience or subjection to authority as opposed to individual freedom: authoritarian principles; authoritarian attitudes.
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