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Interval information
Ratio 8/7
Factorization 23 × 7-1
Monzo [3 0 0 -1
Size in cents 231.17409¢
Names septimal whole tone,
supermajor second,
septimal major second
Color name r2, ru 2nd
FJS name [math]\text{M2}_{7}[/math]
Special properties superparticular,
Tenney height (log2 nd) 5.80735
Weil height (log2 max(n, d)) 6
Wilson height (sopfr (nd)) 13
Harmonic entropy
(Shannon, [math]\sqrt{nd}[/math])
~4.19168 bits

[sound info]
open this interval in xen-calc
English Wikipedia has an article on:

In just intonation, 8/7 is the supermajor second or septimal major second of approximately 231.2 ¢. Although it falls between the familiar major second and minor third of 12edo, it generally sounds more like a wide second than a narrow third. It can be found between the 7th and 8th harmonics and is thus a superparticular ratio. In 7-limit JI and higher, it is treated as a consonance, particularly in the context of a chord such as 4:5:6:7:8, where it appears between the harmonic seventh (7/4) and octave. It differs from the Pythagorean major second of 9/8 by 64/63, a microtone of about 27.3 ¢. It is close in size to one step of 5edo = 240 ¢.

A stack of three supermajor seconds is close to a perfect fifth (3/2). The difference is 1029/1024 (about 8.4 ¢), which is tempered out in slendric and 31edo.

See also