- a combining form meaning “water,” used in the formation of compound words: hydroplane; hydrogen.
Also especially before a vowel, hydr-1.
Origin of hydro-1
< Greek, combining form of hýdōr water
- a combining form representing hydrogen in compound words, denoting especially a combination of hydrogen with some negative element or radical: hydrobromic.
Also especially before a vowel, hydr-2.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
sometimes before a vowel hydr-
- indicating or denoting water, liquid, or fluidhydrolysis; hydrodynamics
- indicating the presence of hydrogen in a chemical compoundhydrochloric acid
- indicating a hydroidhydrozoan
from Greek hudōr water
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Word Origin and History for hydro-
Online Etymology Dictionary, © 2010 Douglas Harper
- Water; liquid:hydrocephalus.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
- A prefix that means: water (as in hydroelectric) or hydrogen, (as in hydrochloride).
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.