D defs.my
Entry 2 senses Webster, 1913

Hydro-

· Hy·dro- · IPA /ˈhaɪ.dɹoʊ/
01 A combining form from Gr. �, �, water (see Hydra).
  1. 1.
    A combining form from Gr. �, �, water (see Hydra). See: Hydra
  2. 2.
    A combining form of hydrogen, indicating hydrogen as an ingredient, as hydrochloric; or a reduction product obtained by hydrogen, as hydroquinone.(Chem.)