For every Visible spectrum (colour) is there also invisible colours?

Paul has the EM spectrum broken down for you. One thing I would like to add is that the light we see in the visible spectrum, is just smaller than one full octave of light. We can hear several octaves of sound, a low E and a high E are similar, I would only imagine that a low blue (in infrared) and what we call blue (visible light) would share similar properties in how we would see them, but they would be different colors, just like the two E's are different notes. To say for certain how a shorter or longer wavelength would be processed by our optical nerves and our brain is impossible, however.