English
hypotonic
From hypo- + tonic.
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 Having a lower osmotic pressure than another.
Language periods are conventional ranges, not dates for this word.
Etymograph / hypotonic