Glossary Term Definition
A system of accentuation using multiple diacritics, as in classical Greek orthography.
Definition
Polytonic refers to an orthographic system that employs multiple accent marks and breathing marks to indicate pitch, stress, and aspiration. Classical Greek is the most prominent polytonic script, using acute, grave, and circumflex accents along with smooth and rough breathings, iota subscripts, and diaereses. Polytonic typography requires typefaces with a full complement of composite characters and careful attention to mark placement. The monotonic simplification adopted for modern Greek in 1982 reduced these to a single accent.
Source
No access — Robert Bringhurst — p. 343:
Having or using several different tonal markers or accents. Classical Greek, for example, is polytonic, while modern Greek is monotonic.