Romex® is a brand of electrical wiring made by Southwire. Romex wiring is sheathed in a plastic coating. It is given its name from the company that originally made it, the Rome Cable Corp. of Rome, New York. The "rome" obviously comes from the company's name and the orgin for the "x" is uncertain. Rome Cable was founded in 1936, and filed for bankruptcy in 2003. Now the Romex brand is owned by Southwire and is an actual trademarked brand.