What does apotome mean?
The definition of apotome
A*pot”o*me, n.
Etym: [Gr.

1 (Math.)
The difference between two quantities commensurable only in power, as between sq. root2 and 1, or between the diagonal and side of a square.
2 (Mus)
The remaining part of a whole tone after a smaller semitone has been deducted from it; a major semitone. [Obs.]