What is a Pylon?

noun
an upright structure that is used for support or for navigational guidance, in particular.

a tower used for carrying power lines high above the ground.

noun: pylon; plural noun: pylons; noun: electricity pylon; plural noun: electricity pylons

a pillarlike structure on the wing of an aircraft used for carrying an engine, weapon, fuel tank, or other load.

a tower or post marking a path for light aircraft, cars, or other vehicles, especially in racing.

a monumental gateway to an ancient Egyptian temple formed by two truncated pyramidal towers.

Protoss structures and, to a lesser extent, units, draw their energy from a great psionic energy matrix that emanates from Aiur. While a nexus provides a link to this matrix, khaydarin crystal-based pylons are needed to actually tap into the energy required to provide psionic energy to new colonies. Each pylon generates a short-ranged aura of energy, which can provide the power needed by structures and warp gates. The use of pylons goes at least as far back as the Second Age. http://starcraft.wikia.com/wiki/Pylon