18-letter words containing o, r, l, a
- triangle of forces — a triangle whose sides represent the magnitudes and directions of three forces whose resultant is zero and which are therefore in equilibrium
- trickle irrigation — drip irrigation.
- tristan und isolde — a music drama (composed, 1857–59; première, 1865) by Richard Wagner.
- trobriand islander — a native or inhabitant of the Trobriand Islands of Papua New Guinea
- turbine ventilator — a ventilator, usually mounted on the roof of a building, deck of a ship, etc., having at its head a globular, vaned rotor that is rotated by the wind, conveying air through a duct to and from a chamber below.
- ulcerative colitis — chronic ulceration in the large intestine, characterized by painful abdominal cramps and profuse diarrhea containing pus, blood, and mucus.
- ultralow frequency — an electromagnetic wave with a frequency between 300 and 3000 hertz. Abbreviation: ULF, ulf.
- ultrasonic testing — the scanning of material with an ultrasonic beam, during which reflections from faults in the material can be detected: a powerful nondestructive test method
- ultrasonic welding — the use of high-energy vibration of ultrasonic frequency to produce a weld between two components which are held in close contact
- ultrasound scanner — a device used to examine an internal bodily structure by the use of ultrasonic waves, esp for the diagnosis of abnormality in a fetus
- ultraviolet filter — a filter used on a lens to absorb ultraviolet radiation that may impart an undesirable blue cast to a photograph.
- under (one's) seal — in a document authenticated by one's seal
- under lock and key — a device for securing a door, gate, lid, drawer, or the like in position when closed, consisting of a bolt or system of bolts propelled and withdrawn by a mechanism operated by a key, dial, etc.
- universal coupling — a coupling between rotating shafts set at an angle to one another, allowing for rotation in three planes.
- unix international — (body) (UI) A consortium including Sun, AT&T and others formed to promote an open environment based on Unix System V, including the Open Look windowing system.
- upper palaeolithic — the latest of the three periods of the Palaeolithic, beginning about 40 000 bc and ending, in Europe, about 12 000 bc: characterized by the emergence of modern man, Homo sapiens
- upper partial tone — overtone (def 1).
- ur of the chaldees — the city where Abraham was born, sometimes identified with the Sumerian city of Ur. Gen. 11:28, 31; 15:7; Neh. 9:7.
- vicar of wakefield — a novel (1766) by Goldsmith.
- victor emmanuel ii — 1820–78, king of Sardinia 1849–78; first king of Italy 1861–78.
- video surveillance — a system of monitoring activity in an area or building using a television system in which signals are transmitted from a television camera to the receivers by cables or telephone links forming a closed circuit
- voluntary abortion — abortion (def 1).
- voluntary-abortion — Also called voluntary abortion. the removal of an embryo or fetus from the uterus in order to end a pregnancy.
- warning coloration — a bold, distinctive pattern of color characteristic of a poisonous or unpalatable organism, as the skunk or the monarch butterfly, that functions as a warning to and defense against predators.
- watson-crick model — a widely accepted model for the three-dimensional structure of DNA, featuring a double-helix configuration for the molecule's two hydrogen-bonded complementary polynucleotide strands.
- weak nuclear force — weak interaction
- western alienation — a feeling of resentment by some inhabitants of western Canada against perceived favouritism by the national government towards the eastern provinces
- western meadowlark — any of several American songbirds of the genus Sturnella, of the family Icteridae, especially S. magna (eastern meadowlark) and S. neglecta (western meadowlark) having a brownish and black back and wings and a yellow breast, noted for their clear, tuneful song.
- wheelchair housing — housing designed or adapted for a chairbound person
- white-collar crime — any of various crimes, as embezzlement, fraud, or stealing office equipment, committed by business or professional people while working at their occupations.
- wild passionflower — the maypop, Passiflora incarnata.
- wildlife programme — (esp on television) a documentary whose subject is wild animals in their natural habitat or undomesticated fauna and flora generally
- wilson's phalarope — a phalarope, Phalaropus tricolor, that breeds in the prairie regions of North America and winters in Argentina and Chile.
- withdrawal symptom — effects of stopping a drug
- woman of the world — a woman experienced and sophisticated in the ways and manners of the world, especially the world of society.
- women's liberation — a movement to combat sexual discrimination and to gain full legal, economic, vocational, educational, and social rights and opportunities for women, equal to those of men.
- world championship — an international competition in a particular sport or activity for people all around the world
- world trade center — New York: business district
- wrangell mountains — a mountain range in SE Alaska, extending into the Yukon, Canada. Highest peak: Mount Blackburn, 5037 m (16 523 ft)
- wrongful dismissal — the act of making someone redundant for reasons which are illegal or unjust
- xenon hexafluoride — a colorless, crystalline compound, XeF 6 , that melts at 50°C to a yellow liquid, and boils at 75°C.
- yellow-green algae — a group of common single-celled and colonial algae of the phylum Chrysophyta, having mostly yellow and green pigments, occurring in soil and on moist rocks and vegetation and also as a slime or scum on ponds and stagnant waters.
- you never can tell — If you say 'You never can tell', you mean that the future is always uncertain and it is never possible to know exactly what will happen.
- zion national park — a park in SW Utah. 148 sq. mi. (383 sq. km).
- zorrilla (y moral) — Joˈsé (hɔˈsɛ ) ; h^ōseˈ) 1817-93; Sp. poet & playwright