1) Musical note 2) Note 3) Tone 
In music or music theory, the supertonic is the second degree or note of a diatonic scale, one step above the tonic. In music theory, the supertonic chord may be symbolized by the Roman numeral ii in a major scale, indicating that the chord is a minor chord (for example, D-F-A in C major), or ii{music|dim} in a natural minor scale, indicating that...
• (n.) The note next above the keynote; the second of the scale.
The note or chord on The second degree of The major scale. this is Often marked with The Roman numeral II
Su`per·ton'ic noun (Mus.) The note next above the keynote; the second of the scale. Busby. 
[n] - (music) the second note of a diatonic scale
noun (music) the second note of a diatonic scale
the second note of a diatonic scale and the chord built on that note.
the second tone of a diatonic scale, being the next above the tonic.