Reference

Names of Degrees

Besides referring to the degrees of the major and minor scales by Roman numbers, the following names may also be used:

Degree Name

I Tonic

II Supertonic

III Mediant

IV Subdominant

V Dominant

VI Submediant or
Superdominant

VII Leading tone

Degree	Name
I	Tonic
II	Supertonic
III	Mediant
IV	Subdominant
V	Dominant
VI	Submediant or Superdominant
VII	Leading tone

The IV degree is called subdominant because it is a fifth below the tonic while the dominant is a fifth above the tonic. The III degree is called mediant because it is midway between the tonic and the dominant. The VI degree is called submediant because it is midway between the tonic and the subdominant.