from lat. second – second
1) The interval formed by the adjacent steps of the musical scale; denoted by the number 2. They differ: a major second (b. 2), containing 1 tone, a small second (m. 2) – 1/2 tones, incremental second (amp. 2) – 11/2 tones, diminished second (d. 2) – 0 tones (enharmonic equal to pure prime). The second belongs to the number of simple intervals: minor and major seconds are diatonic intervals formed by the steps of the diatonic scale (mode), and turn into major and minor sevenths, respectively; diminished and augmented seconds are chromatic intervals.
2) Harmonic double sound, formed by the sounds of neighboring steps of the musical scale.
3) The second step of the diatonic scale.
V. A. Vakhromeev