The Latest wordsmith posting was for TAXIS. The source is said to be from “From Greek taxis (arrangement, order), from tassein (to arrange)”. Many years ago I remember seeing a TV program about the succession of various aristocratic families in Europe. One was about the family “Thurn und Taxis”. The Wikipedia reference is http://en.wikipedia.org/wiki/Thurn_und_Taxis. The program explained the postal service the Thurn und Taxis family started. Because of their courier system, the picking up of people – not just mail – became known as a TAXI.

So the uses of the word TAXIS when not plural has an entirely different meaning that the singular TAXI.