coaxial cable

from The American Heritage® Dictionary of the English Language, 4th Edition

• n. A cable consisting of a conducting outer metal tube that encloses and is insulated from a central conducting core, used primarily for the transmission of high-frequency signals. Also called coaxial line.

from Wiktionary, Creative Commons Attribution/Share-Alike License

• n. A transmission line, consisting of a conducting wire surrounded by an insulated spacer, surrounded by a cylindrical conducting sheath; used to carry high frequency signals such as TV.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• n. a transmission line for high-frequency signals