15-letter words containing t, w, a, i
- the-night-watch — a painting (1642) by Rembrandt.
- thorndike's law — the principle that all learnt behaviour is regulated by rewards and punishments, proposed by Edward Lee Thorndike (1874–1949), US psychologist
- titius-bode law — Bode's law.
- to carry weight — If a person or their opinion carries weight, they are respected and are able to influence people.
- touch base with — the bottom support of anything; that on which a thing stands or rests: a metal base for the table.
- towers of hanoi — (games) A classic computer science problem, invented by Edouard Lucas in 1883, often used as an example of recursion. "In the great temple at Benares, says he, beneath the dome which marks the centre of the world, rests a brass plate in which are fixed three diamond needles, each a cubit high and as thick as the body of a bee. On one of these needles, at the creation, God placed sixty-four discs of pure gold, the largest disc resting on the brass plate, and the others getting smaller and smaller up to the top one. This is the Tower of Bramah. Day and night unceasingly the priests transfer the discs from one diamond needle to another according to the fixed and immutable laws of Bramah, which require that the priest on duty must not move more than one disc at a time and that he must place this disc on a needle so that there is no smaller disc below it. When the sixty-four discs shall have been thus transferred from the needle on which at the creation God placed them to one of the other needles, tower, temple, and Brahmins alike will crumble into dust, and with a thunderclap the world will vanish." The recursive solution is: Solve for n-1 discs recursively, then move the remaining largest disc to the free needle. Note that there is also a non-recursive solution: On odd-numbered moves, move the smallest sized disk clockwise. On even-numbered moves, make the single other move which is possible.
- training wheels — a pair of small wheels attached one on each side of the rear wheel of a bicycle for stability while one is learning to ride.
- transfer window — the period during the year in which a football club can transfer players from other teams into their own
- travelling wave — a wave carrying energy away from its source
- trigger warning — a stated warning that the content of a text, video, etc., may upset or offend some people, especially those who have previously experienced a related trauma: a blog post with a trigger warning for rape.
- twist one's arm — to combine, as two or more strands or threads, by winding together; intertwine.
- twitching trail — a logging road sufficiently developed to allow the hauling of logs along it by horse or tractor.
- two-dimensional — having the dimensions of height and width only: a two-dimensional surface.
- unanswerability — the quality of not being answerable or contestable
- unseaworthiness — constructed, outfitted, manned, and in all respects fitted for a voyage at sea.
- upward mobility — movement from one social level to a higher one (upward mobility) or a lower one (downward mobility) as by changing jobs or marrying.
- vatican swindle — Lafcadio's Adventures.
- venetian window — Palladian window.
- wage indexation — the linking of wages to an index representing the cost of living, so that they are automatically adjusted up or down as that rises or falls
- walk-in traffic — The walk-in traffic of a store is the number of people who choose to visit it as they pass by.
- walking catfish — an Asian catfish, Clarias batrachus, that can survive out of water and move overland from one body of water to another: introduced into Florida.
- wallace nutting — Wallace, 1861–1941, U.S. antiquary, author, and illustrator.
- walpurgis night — (especially in medieval German folklore) the evening preceding the feast day of St. Walpurgis, when witches congregated, especially on the Brocken.
- warrant officer — (in the U.S. Armed Forces) an officer of one of four grades ranking above enlisted personnel and below commissioned officers.
- washington lily — a lily, Lilium washingtonianum, of the western coast of the U.S., having whorled leaves and fragrant, purple-spotted white flowers.
- washington palm — a palm tree, Washingtonia filifera, of California and Florida, having large fan-shaped leaves and small black fruits
- watch committee — a local government committee composed of magistrates and representatives of the county borough council responsible for the efficiency of the local police force
- water authority — an official body which is responsible for providing water
- water pimpernel — the brookweed.
- water pollution — the pollution of the sea and rivers
- water-resistant — resisting though not entirely preventing the penetration of water.
- weather station — an installation equipped and used for meteorological observation.
- weatherboarding — an early type of board used as a siding for a building.
- weatherproofing — Present participle of weatherproof.
- wedding banquet — a lavish meal served after a wedding ceremony
- weight training — weightlifting done as a conditioning exercise.
- welfare statism — the belief in or practices of a welfare state.
- well-accredited — officially recognized as meeting the essential requirements, as of academic excellence: accredited schools.
- well-acquainted — having personal knowledge as a result of study, experience, etc.; informed (usually followed by with): to be acquainted with law.
- well-advertised — to announce or praise (a product, service, etc.) in some public medium of communication in order to induce people to buy or use it: to advertise a new brand of toothpaste.
- well-cultivated — prepared and used for raising crops; tilled: cultivated land.
- well-delineated — to trace the outline of; sketch or trace in outline; represent pictorially: He delineated the state of Texas on the map with a red pencil.
- well-integrated — combining or coordinating separate elements so as to provide a harmonious, interrelated whole: an integrated plot; an integrated course of study.
- well-maintained — to keep in existence or continuance; preserve; retain: to maintain good relations with neighboring countries.
- well-ventilated — to provide (a room, mine, etc.) with fresh air in place of air that has been used or contaminated.
- westphalian ham — a hard German ham with a distinctive flavor derived from being smoked over beechwood and juniper.
- whaling station — a place where the carcases of whales were processed
- what's cooking? — what's happening?
- what's-his-name — man: forgotten name
- whatchamacallit — an object or person whose name one does not know or cannot recall.