The correct term is retronimo, with tilde. It means outdated or old-fashioned term, which was modified. Term that must be supplemented to clarify it. It usually requires a complement to be accurate the definition that is intended, since it is considered that by modernity has been modified. A classic example is guitar : before the invention of the electric guitar it was not necessary to specify the type of guitar, that is why today to refer to a common or classical guitar, we must use as a retronimo : acoustic guitar, to be able to differentiate .