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A cone is a shape with a round bottom that gets smaller as it goes until it reaches a point. If you cut a slice through a cone parallel to the bottom, it will be the same shape as the bottom. If you cut a slice through the cone vertically going through the top point, you will get a triangle.
Many things are cone shaped. volcanos tend to be cone-shaped, pinecones and pine trees like the ones in the picture are cone-shaped, and of course traffic cones are cone shaped.

Cone rhymes with ...

Headphones, Groan, Soapstone, Overblown, Brimstone, Microphone ... see all