APOTOME

‖A‐pot″o‐me (�), n. [] 1. 1. (Math.) The difference between two quantities commensurable only in power, as between √2 and 1, or between the diagonal and side of a square.
2. 2. (Mus) The remaining part of a whole tone after a smaller semitone has been deducted from it; a major semitone.