Jankó keyboard

Etymology
Designed by Paul von Jankó, a Hungarian pianist and engineer, in 1882.

Noun

 * 1)  A kind of piano keyboard that, instead of one long row of keys, has an array of keys consisting of two interleaved manuals with three touch-points for every key lever, making six rows of keys. Each vertical column of three keys is a semitone away from the neighboring ones, which are in the alternate rows.