What does diesis mean?
A diesis is one of the smallest named intervals in Western music theory. In its classical sense it denotes the tiny gap — about a quarter of a tone — between an enharmonically equivalent pair of notes, such as the difference between three stacked perfect fifths and a two-octave span, expressed in just intonation by the ratio 128:125. Composers and theorists working with microtones use dieses to divide the semitone into finer steps, giving the word a niche but precise role in discussions of tuning systems. Separately, in Greek typography the diesis is the double dagger mark (‡), a reference symbol akin to the asterisk and single dagger. The word comes from the Greek díesis, meaning 'a letting through' or 'passage', and its plural is "dieses". Though rarely heard outside specialist circles, it rewards anyone curious about how finely music can be measured — and offers a pleasing reminder that even punctuation has a vocabulary of its own.
A minute musical interval, especially the enharmonic diesis (ratio 128:125 in just intonation, roughly 41 cents) or any similarly small division of the semitone in microtonal theory.
"Ancient Greek theorists described the diesis as the smallest perceptible step in their tetrachord divisions."
Almost exclusively found in academic and specialist writing on tuning theory; define on first use.
In Greek typography, the double dagger symbol (‡) used to mark footnotes or references.
"The editor inserted a diesis beside the variant reading in the marginal apparatus."
The plural follows the Greek second declension: singular "diesis", plural "dieses". Note that "dieses" is identical to the German demonstrative pronoun but unrelated to it.
"The scale was built from twelve equal dieses spanning the octave."
In Greek printing shops, the 'diesis' isn't a sound at all — it's the double dagger ‡ that marks footnotes.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of diesis
Diesis derives from the ancient Greek díesis, meaning 'a sending through' or 'discharge', formed on the verb iénai, 'to go'. It entered English scholarly writing during the Renaissance revival of Greek learning, when theorists translated classical accounts of intervals. The same Greek root yields cognates such as dieresis ('a dividing'), while Latin relatives of ienai give English words like 'exit' and 'transit'.
How diesis is actually used
"Dieses" is a rare technical term encountered mainly in music theory texts dealing with just intonation and microtonality, and in discussions of Greek typographic convention. Its plural, "dieses", follows the Greek-style declension. Because it is obscure, writers should define it on first use for general audiences.
Easily confused with diesis
A diaeresis (¨) is the two-dot mark placed over a vowel to show it is pronounced separately, while a diesis is either a tiny musical interval or the Greek name for the double dagger (‡).
A comma is the small tuning discrepancy left after stacking perfect fifths, whereas a diesis specifically denotes an enharmonic or microtonal interval such as the difference between three fifths and an octave.