An electrical switch, in a generator or motor, that periodically reverses the direction of an electric current.
A binary map in a given group G, given by [g, h] = ghg⁻¹h⁻¹, where g and h are elements of G, which yields the group's identity if and only if the group operation commutes for g and h.
A binary map in a given ring R, given by [a, b] = ab − ba, where a and b are elements of R, which yields the ring's zero element if and only if the multiplication operation commutes for a and b.
A contact on an electrical device (such as a battery) at which electric current enters or leaves.
A telescope used to identify birds, aeroplanes or wildlife.
Either of the two points on the earth's surface around which it rotates; also, similar points on any other rotating object.
A construction by which an animal is harnessed to a carriage.
A gun.
Either of the states that characterize a bipolar disorder.
A point of magnetic focus, especially each of the two opposing such points of a magnet (designated north and south).
A fixed point relative to other points or lines.
Originally, a stick; now specifically, a long and slender piece of metal or (especially) wood, used for various construction or support purposes.
A type of basic fishing rod.
A long sports implement used for pole-vaulting; now made of glassfiber or carbon fiber, formerly also metal, bamboo and wood have been used.
Pole position.
For a meromorphic function f(z), any point a for which f(z)→∞ as z→a.
A unit of length, equal to a rod (¹⁄₄ chain or 5+¹⁄₂ yards).
A penis.
To propel by pushing with poles, to push with a pole.
To furnish with poles for support.
To identify something quite precisely using a telescope.
To convey on poles.
To stir, as molten glass, with a pole.
To strike (the ball) very hard.
To induce piezoelectricity in (a substance) by aligning the dipoles.