Scale Degree Names
Musicians often refer to scale degrees by a set of traditional names rather than numbers.  Notice that the seventh scale degree has two different names, depending on whether it is raised or lowered.

The origin of some of these names is not what you would expect.  For example, subdominant does not mean "below the dominant."  The chart illustrates the concept of a dominant a perfect fifth above the tonic, and another a perfect fifth below.  The mediants follow the same concept.