Pronunciation: (hī'drō), [key]
—n., pl. -dros for 2, 3,
1. Informal.hydroelectric power.
a. a bathhouse, hotel, or resort catering to people taking mineral-water health cures; spa.
b. an establishment furnishing hydrotherapy.
Informal.of, pertaining to, or furnishing water, water power, or hydroelectricity: funds for new hydro projects.
a combining form meaning “water,” used in the formation of compound words: hydroplane; hydrogen. Also, esp. before a vowel,hydr-1.
a combining form representing hydrogen in compound words, denoting esp. a combination of hydrogen with some negative element or radical: hydrobromic. Also, esp. before a vowel,hydr-2.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.