Syntonic temperament

The syntonic temperament is a system of musical tuning in which the frequency ratio of each musical interval is a product of powers of an octave and a tempered perfect fifth, with the width of the tempered major third being equal to four tempered perfect fifths minus two octaves and the width of the tempered major second being equal to two tempered perfect fifths minus one octave (i.e., half the width of the major third).

Alternatively put, the syntonic temperament:

This is the same definition as that of the meantone temperament. The syntonic temperament can be viewed as a systematic extension of the meantone temperament beyond the range imposed by the meantone temperament's need to remain consonant with timbres that conform to the harmonic series.

The syntonic temperament is named after the syntonic comma, as that is the first comma tempered to unison in its comma sequence.