Tritone

The tritone is the name of a musical interval that is made up of three whole tones. In 12edo the tritone is exactly 600 cents, or sqrt(2). As such, the term is also used generally to refer to any pitch in the neighborhood of 600c, or roughly halfway between 4/3 and 3/2.

In non-12 tunings, and particularly in JI, there are a number of different tritones which have subtly different flavors, such as 7/5 and 10/7. The temperament eliminating 50/49 is of particular interest in that it equates these two tritones, and provides a JI basis for the 12-EDO concept of the "tritone substitution."