Subdominant
A whole tone that is one step below the dominant of a key.
Whole Tone
1. An interval consisting of two semitones, that is a whole step.
2. The particular sound of an instrument or voice, as well as the performer's particular coloring of that sound. For example, the tone produced by a certain clarinetist could be said to be rich, dark, and mellow; this is the result of the natural sound of the instrument, combined with the performer's particular technique of playing.
Step
An interval of a second. Within the context of a scale, a step is the interval between one degree and the next, regardless if it is a major, minor, augmented, or diminished second.
Key
A specific scale or series of notes defining a particular tonality. Keys may be defined as major or minor, and are named after their tonic or keynote. Thus the series of notes with intervals defining a major tonality and based on the key of C is the key of C major.