1. Of or relating to a proto-language or the earliest reconstructed form of a language family.
Usage: linguistics; technical
2. In music, relating to or denoting the first tone or tonic of a scale in its original or primitive form.
Usage: music; rare

Examples

• Linguists study prototonic features to understand how ancient language families evolved.
• The prototonic reconstruction of Indo-European helps scholars trace word origins across modern languages.
• Comparative analysis of prototonic forms reveals sound changes over centuries.
• Researchers debate the prototonic vowel system of the ancestral language.