It may also be called the Pythagorean apotome or the Pythagorean major semitone.

This concept of the Apotome appears in book X of Euclid's Elements.

Advanced microscopy image generation by optical sectioning and structured illumination, by Carl Zeiss, Inc (ApoTome).

Although closer in size to the Pythagorean apotome than to the limma, it has been so called because of its function as a diatonic semitone rather than a chromatic one.

In Pythagorean tuning, these correspond to the Pythagorean limma and the Pythagorean apotome, only now the apotome is larger.

Although the limma and the apotome are both represented by one step of 12-pitch equal temperament, they are not equal in Pythagorean tuning, and their difference, 531441/524288, is known as the Pythagorean comma.

The Pythagorean limma and Pythagorean apotome are enharmonic equivalents (chromatic semitones) and only a Pythagorean comma apart, in contrast to diatonic and chromatic semitones in meantone temperament and 5-limit just intonation.