Geometry Glossary

•  Note: Glossaries only account for terms that do not require a full lesson for adequate explanation. To find a term, search at the homepage.

circumference – The length or distance around a circle. The perimeter of a circle.
lateral surface – a lateral surface of a solid is the face or surface of the solid on its sides, that is, any face or surface that is not a base. For a cylinder or cone the lateral surface would be the curved portions for both.
longitudinal axis – an imaginary line running through the center of a body, typically through the longest dimension of the body. For example, in humans the longitudinal axis would run from the the head through the body and through between the legs, in an aircraft the longitudnal axis might run from the nose of the aircraft through to the back. On earth the longitude lines run from north to south. If the head is considered the north pole and the tail the south pole, and with the airplane the head is the nose and the tail is the exhaust end, then, in all three cases the longitudinal axis can be thought of as the line running from head to tail, to make it easy to remember. (picture)
parallelepiped – (pronounced parallel-e-pie-ped) a three dimensional figure formed by six parallelograms. A parallelepiped can be defined as one of the three following: (1) a polyhedron with six faces (hexahedron), each of which is a parallelogram, (2) a hexahedron with three pairs of parallel faces, and (3) a prism of which the base is a parallelogram.
perimeter – The distance around the outside of a polygon. The circumference, border, or outer boundary of a two-dimensional figure. .
transverse plane – The transverse plane is a plane perpendicular to the longitudinal axis. (picture)
transverse section – A section cut using a transverse plane