There are 20 9-letter words that start with 'hydro'.
| hydrocast | hydrocele | hydrofoil |
| hydrogels | hydrogens | hydrolase |
| hydrology | hydrolyte | hydrolyze |
| hydromels | hydronium | hydropath |
| hydropses | hydrosere | hydroskis |
| hydrosols | hydrostat | hydroxide |
| hydroxyls | hydrozoan | |
Note: These 20 9-letter words that start with 'hydro' are found from the USA & Canada version of the tournament Scrabble word list.
Also see words start with hydrop, hydroc, hydrox, hydrol, hydrog, hydros, hydrom, hydrot, hydrob, hydrod, hydron, hydrof, hydroi, hydroq, hydroz, hydroe, hydrok, hydrou.
6-letter words start with 'hydro' (1)