English
hydrocyanic
From hydro- + cyanic.
Proto-Indo-European *wed- ‘water’
Proto-Indo-European *wódr̥ ‘water’
Proto-Hellenic *údōr ‘water’
Ancient Greek ῡ̆̔́δωρ ‘water’
English hydro-
Today it means
adj Of or pertaining to hydrocyanic acid or its compounds
Language periods are conventional ranges, not dates for this word.
Etymograph / hydrocyanic