the oceans, lakes, rivers, etc. of a region, esp. as dealt
with on a map
or in a survey, treatise
Webster’s New World College Dictionary, 4th Edition. Copyright © 2010 by
Houghton Mifflin Harcourt. All rights reserved.
Derived forms hydrographer (hyˈdrographer)
hydrographic (ˌhydroˈgraphic) (ˌhaɪdroʊˈgræfɪk
adjective or ˌhydroˈgraphical