Geometry

2. an object, shape, or arrangement in the form of a pyramid.
4. a plane figure with four equal straight sides and four right angles.
5. a round plane figure whose boundary (the circumference) consists of points equidistant from a fixed point (the center).
6. a solid geometric figure with straight parallel sides and a circular or oval cross section.
9. a plane figure with at least three straight sides and angles, and typically five or more.
11. a plane figure with five straight sides and five angles.
14. a plane figure with three straight sides and three angles.
16. a four-sided plane rectilinear figure with opposite sides parallel.
17. a quadrilateral with only one pair of parallel sides.
19. a triangle in which one of the angles is an obtuse angle.
20. a plane figure with ten straight sides and angles.

1. a round solid figure, or its surface, with every point on its surface equidistant from its center.
3. a plane figure with four straight sides and four right angles, especially one with unequal adjacent sides, in contrast to a square.
7. a plane figure with nine straight sides and nine angles.
8. a triangle with a right angle.
10. a plane figure with eight straight sides and eight angles.
12. a triangle with three acute angles, that means they measure less than 90°.
13. a plane figure with six straight sides and angles.
15. neither parallel nor at right angles to a specified or implied line; askew; crooked.
18. side by side and having the same distance continuously between them.