geometry

3. a solid geometric figure with straight parallel sides and a circular or oval cross section.
5. the conceptual operation of turning a system around an axis.
8. a round solid figure, or its surface, with every point on its surface equidistant from its center.
10. a solid geometric figure whose two end faces are similar, equal, and parallel rectilinear figures, and whose sides are parallelograms.
12. a plane figure with three straight sides and three angles.
14. the action or condition of becoming or being made wider, larger, or more open.

1. the exact middle point.
2. a plane figure with four equal straight sides and four right angles.
4. a parallelogram with opposite equal acute angles, opposite equal obtuse angles, and four equal sides
5. any of a set of straight lines passing through one point.
6. each angular point of a polygon, polyhedron, or other figure.
7. a plane figure with four straight sides and four right angles, especially one with unequal adjacent sides, in contrast to a square.
9. a solid or hollow object which tapers from a circular or roughly circular base to a point.
11. a straight line drawn from any vertex of a triangle to the middle of the opposite side.
13. a round plane figure whose boundary (the circumference) consists of points equidistant from a fixed point (the center).