The word “chromatic” comes from the Greek word “chromos” meaning “color”. Organists in the 16th and 17th centuries such as Sweelinck liked to write “Chromatic Fantasias”. These were pieces based on tunes which were chromatic. In those days, because of the tuning systems used, not all the semitones were exactly the same size. Going up a chromatic scale would have been like walking up a staircase with steps which were slightly larger or smaller in depth. This made chromatic scales very interesting and “colourful” which is why they were called “chromatic”.