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black triangle

1. An unidentified flying object (popularly known as a UFO) in the shape of a dark triangle, typically with points of light in each corner. I know you think I'm crazy, but every spring, I see those black triangles appearing over my corn fields at night!
2. In Nazi Germany, a badge assigned to concentration camp inmates considered "asocial" or mentally unfit for work. Her clinical depression, which was vilified by the Nazis, meant she had to wear a black triangle in the concentration camp.
See also: black, triangle

eternal triangle

A sexual encounter or relationship between three people. Although exciting at first, the eternal triangle caused their relationship to suffer and ultimately end.
See also: eternal, triangle
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.

(the) eternal triangle

a sexual or emotional relationship involving two women and one man or two men and one woman. (*Typically, a couple [man and woman] and another man or woman.) Henry can't choose between his wife and his mistress. It's the eternal triangle. I'm surprised Jane doesn't get tired of the eternal triangle. She goes out with Peter at the weekend and Jim during the week.
See also: eternal, triangle
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.

eternal triangle

A relationship involving three lovers, such as two women involved with one man or two men with one woman. For example, The plot of the murder mystery revolved around the eternal triangle of a husband, wife, and another woman . [c. 1900]
See also: eternal, triangle
The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

eternal triangle

a relationship between three people, typically a couple and the lover of one of them, involving sexual rivalry.
See also: eternal, triangle
Farlex Partner Idioms Dictionary © Farlex 2017

eternal triangle, the

A threesome of lovers, either two men involved with or vying for one woman or two women and one man. “Eternal” here simply means that this situation has occurred over and over through the ages. The term has been traced to a book review appearing in the London Daily Chronicle in 1907, describing a novel that “deals with the eternal triangle, which, in this case, consists of two men and one woman.”
See also: eternal
The Dictionary of Clichés by Christine Ammer Copyright © 2013 by Christine Ammer
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References in periodicals archive ?
Equilateral triangles are those in which all three angles are 60[degrees], and all sides are the same length.
This will allow your triangles to connect in a circle in the next step.
Pat then asked the class if anyone made a triangle with sides of 1, 1 and 18 matchsticks.
The Philippines, being at the apex of the Coral Triangle, is a partner-nation of the Coral Triangle Initiative on Coral Reefs, Fisheries and Food Security (CTI-CFF).
Next, pin and cut out as many triangles as you can.
The Cream Triangle Slices are served pre-cut for convenience, in both traditional and innovative flavours.
In Section 4, two heuristics strategies and an approximate algorithm for solving triangle packing problem are proposed.
When a unit equilateral triangle is tangent to another unit equilateral triangle, zero, one, or two angle regions may be formed, which is shown in Figures 3, 4, and 5(a)-5(c), respectively.
Located off the South-Eastern coast of the USA and in the Atlantic Ocean is the Bermuda Triangle. To be more specific the three corners of Miami (Florida), San Juan (Puerto Rico) and Bermuda (the north-Atlantic island) form the Bermuda Triangle.
Definition 2.1 A Gelfand-Tsetlin triangle of size n is a triangular array X = [([X.sub.i,j]).sub.n[greater than or equal to]i[greater than or equal to]f[greater than or equal to]i] of positive integers
Called The Kobon Triangle Puzzle, it is named after the Japanese puzzle expert Kobon Fujimura.
The orthocentric tetrahedron of triangle [8], [7] is a simple construction which gives students a great opportunity for in-depth study of perpendicularity in space and testing of various methods of proof.
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India, July 27 -- French high-end loudspeaker maker Triangle has entered into a partnership with Delhi-based FX Entertainment, under which FX Entertainment has been appointed the "Exclusive Distributor" for Triangle's premium range of loudspeakers in India.