English
eutonic
From eu- + tonic.
Proto-Indo-European *h₁su- ‘good’
Proto-Hellenic *ehu- ‘good’
Ancient Greek ἐΰς ‘good, brave, noble’
Ancient Greek εὖ ‘well, good’
English eu-
Proto-Indo-European *ten- ‘to stretch, extend’
Proto-Indo-European *tónos ‘something stretched’
Proto-Hellenic *tónos ‘rope, cord’
Ancient Greek τόνος ‘a cord, rope or string’
Ancient Greek τονικός ‘tonic, accentual’
English tonic
Today it means
adj Pertaining to normal muscle tone.
Language periods are conventional ranges, not dates for this word.
Etymograph / eutonic