Using or having several musical tones; polytonal.
2Of a language: using or having several vocal tones.
3Designating a system of orthography used to write Greek, incorporating acute, grave and circumflex accent marks, in standard use since the 3rd century b.c. Compare "monotonic".
The polytonic system was intended to represent the distinct pitch accents of ancient Greek. These accents gave way in speech to a single stress accent in medieval and modern Greek, but the three accent marks remained standard in writing until they were replaced by the monotonic system as the official form of written Greek in 1982.
Late 19th century; earliest use found in The Ladies' Repository. From poly- + tonic, after polytone.