a shape that curves or bulges outward | convex shape; convexity; |

a slight convexity (as of the surface of a road) | camber; |

a slight convexity in the shaft of a column; compensates for the illusion of concavity that viewers experience when the sides are perfectly straight | entasis; |

a shape having one or more sharp angles | angular shape; angularity; |

a shape that curves or bends inward | concave shape; concavity; incurvation; incurvature; |

a solid bounded by a cylindrical surface and two parallel planes (the bases) | cylinder; |

a shape that is curved and without sharp angles | round shape; |

a rounded spherical form | conglobation; conglomeration; |

a plane figure with rounded sides curving inward at the top and intersecting at the bottom; conventionally used on playing cards and valentines | heart; |

a closed plane figure bounded by straight sides | polygon; polygonal shape; |

an equiangular polygon | isogon; |

a polygon such that no side extended cuts any other side or vertex; it can be cut by a straight line in at most two points | convex polygon; |

a polygon such that there is a straight line that cuts it in four or more points | concave polygon; |

a polygon with one or more reentrant angles | reentering polygon; reentrant polygon; |

a polygon with all sides and all angles equal | regular polygon; |

a shape resulting from distortion | distorted shape; distortion; |

an ill-defined or arbitrary shape | amorphous shape; |

the trace of a point whose direction of motion changes | curve; curved shape; |

a curve (such as a circle) having no endpoints | closed curve; |

a closed curve that does not intersect itself | jordan curve; simple closed curve; |