An optical illusion depicting an impossible solid object made of three straight beams of square cross section which meet pairwise at right angles at the vertices of the triangle they form.

(mathematics, engineering) A function or waveform that alternately ramps linearly upwards and then downwards.

plural of triangle wave

A region of Bolivia, Chile, Argentina, in the Atacama Desert, which produces much of the world's lithium supply, and contain most of the known world lithium reserves

An area that is dangerous and where people or vessels may disappear. / A set of three things considered dangerous.

A region of West Yorkshire, between Wakefield, Morley and Rothwell, famous for producing early forced rhubarb.

A right-angled triangular array of the natural numbers, whose generation is often set as an exercise in computer science education.

Used other than figuratively or idiomatically: see black, triangle. / (ufology) One of a class of triangle-shaped unidentified flying objects, usually with a light in each corner.

(anatomy) An anatomic space bordered by the common hepatic duct, the cystic duct and base of the liver. It is used to identify the cystic artery.

Synonym of Devil's Sea