equilateral

play
adjective equi·lat·er·al \ˌē-kwə-ˈla-tə-rəl, ˌe-, -ˈla-trəl\

Definition of equilateral

  1. 1 :  having all sides equal <an equilateral triangle> <an equilateral polygon> — see triangle illustration

  2. 2 :  having all the faces equal <an equilateral polyhedron>

Did You Know?

Since equi- means "equal", the meaning of equilateral is easy to guess from its roots. The word is mostly used in geometry. The standard polygons (many-sided geometrical shapes)—the pentagon, hexagon, octagon, etc.—are assumed to be equilateral if we don't say otherwise; an equilateral rectangle has the special name square. But triangles are particularly important, and many triangles are not equal-sided. The standard polyhedrons (many-sided solids) are also equilateral. Most common is the cube, all of whose sides are square. The tetrahedron has four triangular sides and thus is a pyramid with a triangular base, unlike the pyramids of Egypt with their square bases.

Origin and Etymology of equilateral

Late Latin aequilateralis, from Latin aequi- + later-, latus side — more at lateral


First Known Use: 1570

Other Mathematics and Statistics Terms



EQUILATERAL Defined for Kids

equilateral

play
adjective equi·lat·er·al \ˌē-kwə-ˈla-tə-rəl, ˌe-kwə-\

Definition of equilateral for Students

  1. :  having all sides or faces equal <an equilateral triangle>


Learn More about equilateral


Seen and Heard

What made you want to look up equilateral? Please tell us where you read or heard it (including the quote, if possible).

WORD OF THE DAY

very important or noticeable

Get Word of the Day daily email!

WORD GAMES

Take a 3-minute break and test your skills!

  • alphabet-magnets
  • Which is the correct spelling?
Name That Thing

Test your visual vocabulary with our 10-question challenge!

TAKE THE QUIZ
SCRABBLE® Sprint

Test Your Knowledge - and learn some interesting things along the way.

TAKE THE QUIZ