Discant (Latin: discantus, meaning "singing apart") was a style of liturgical setting in the Middle Ages, associated with the development of the Notre Dame school of polyphony. It is a style of organum that includes a plainchant tenor part, with a "note against note" upper voice, moving in contrary motion. It is not a musical form, but rather a technique. "English discant is three-voice parallelism in first-inversion triads."
- Both the tenor and upper parts move at about the same rate, using the equalitas punctorum (an approximately equal rate of movement in all the voices) with between one and three notes in the upper part to every note in the tenor part. At the end of a phrase however, in discant style, the upper part may have more notes, thus producing a more melismatic passage at a cadence.
- Throughout the discant passages, the two parts interchange between consonant intervals: octaves, fifths.
- Discant style is characterised by the use of rhythmic modes throughout each part. In earlier types of organum, rhythm was either not notated as in organum purum, or notated in only the upper voice part, however Notre Dame composers devised a way of notating rhythm using ligatures and six different types of rhythmic modes.
Examples of this can be found in some of Léonin’s late 12th century settings. These settings are often punctuated with passages in discant style, where both the tenor and upper voice move in modal rhythms, often the tenor part in mode 5 (two long notes) and the upper part in mode 1 (a long then short note). Therefore it is easier to imagine how discant style would have sounded, and we can make a guess as to how to recreate the settings. It is suggested by scholars such as Grout, that Léonin used this non-melismatic style in order to mirror the grandeur of Notre Dame Cathedral itself.
Current research suggests that the word 'discantus' was formed with the intention of providing a separate term for a newly developed type of polyphony.
Discant in three or four voices 
The development of modal rhythms enabled the progression from two part discant style to three and four part discant style. This is because, only voices, confined to a set rhythm can be combined effectively to make a set phrase. This was mainly related to Pérotin, around 1200. The parts in these three and four past settings were not necessarily related to each other. Evidence suggests that the parts were either related to the tenor part, or composed independently. Either way, this formed the first ‘composition’, and provided a foundation for development, and a new style, conductus was developed from the three and four part discant ideas.
- White, John D. (1976). The Analysis of Music, p.128. ISBN 0-13-033233-X. Emphasis added.