The number of points at which current can enter a switch; for example, single pole, double pole, and three pole.
A singularity of an analytic function where it behaves very nearly like a rational function. If the function is bounded around a singularity the latter is called removable.
Usually the coldest regions on a planet, being the areas around an axis through the planet perpendicular to the plane of rotation about the Sun.
The sections of a field magnet where the flux lines are concentrated; also where they enter and leave the magnet.
An old English unit of length. Also known as a Rod.