English
hydroplethysmometer
From hydro- + plethysmometer.
Formed from hydro- + plethysmometer
Proto-Indo-European *wed- ‘water’
Proto-Indo-European *wódr̥ ‘water’
Proto-Hellenic *údōr ‘water’
Ancient Greek ῡ̆̔́δωρ ‘water’
English hydro-
Proto-Indo-European *pleh₁- ‘to fill’
Ancient Greek πληθύς ‘throng’
Ancient Greek πληθύνω ‘I increase’
Ancient Greek πληθυσμός ‘increase’
English plethysmometer
Today it means
noun A plethysmometer that employs water
Language periods are conventional ranges, not dates for this word.
Etymograph / hydroplethysmometer