Longman Dictionary of Contemporary English
Wiktionary
n. (context geometry English) A triangle having all three sides equal.
WordNet
n. a three-sided regular polygon [syn: equiangular triangle]
Wikipedia
{4} a^2 | angle = 60°}} In geometry, an equilateral triangle is a triangle in which all three sides are equal. In the familiar Euclidean geometry, equilateral triangles are also equiangular; that is, all three internal angles are also congruent to each other and are each 60°. They are regular polygons, and can therefore also be referred to as regular triangles.
Usage examples of "equilateral triangle".
These fit together and form a perfect equilateral triangle, as shown in the second diagram.
Take for example an equilateral Triangle - who represents with us a Tradesman of the respectable class.
The balls were at the apices of an equilateral triangle about two feet on each side.
At three miles to a side, an equilateral triangle would have an area of approximately four and a half square miles.
Now they were arrayed around the well at the cardinal points of an equilateral triangle, as if waiting for something to emerge from the still, black water.
Spheres are placed between them, forming an equilateral triangle with the sphere of the pommel.
The two forelegs were set wide apart, so that the beast's small, clawed hooves formed almost an equilateral triangle.
One audacious but perfectly realisable idea: a gigantic equilateral triangle would have its 600-mile-long sides sown with potatoes.
In this way a vast yellow circle, surrounded by a green equilateral triangle, would appear every summer.