noun: (mathematics, geometry) The difference between two quantities or lengths commensurable only in power, as between 1 and the square root of 2, or between the diagonal and side of a square.
noun: (music) The remaining part of a whole tone after a smaller semitone has been deducted from it; a major semitone.
noun: (zoology) A distinct division of an insect which is divided from the other divisions by a pinch point.
