An alternative or variant form of diaphonic, meaning relating to or having the quality of diaphony.
Same root as diaphonic (Greek dia- + phone), with the addition of the -al suffix to create an adjectival form, following Latin and Romance language patterns.
The existence of both 'diaphonic' and 'diaphonical' shows how English borrowed words from music theory sometimes developed multiple acceptable forms—this redundancy eventually made 'diaphonic' the preferred modern term.
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