inundate (v.)

"an overflowing, a flood," early 15c., from Latin inundationem (nominative inundatio) "an overflowing," noun of action from past-participle stem of inundare "to overflow," from in- "onto" (from PIE root *en "in") + undare "to flow," from unda "a wave," from PIE *unda-, nasalized form of root *wed- (1) "water; wet."

Proto-Indo-European root meaning "water; wet."

It forms all or part of: abound; anhydrous; carbohydrate; clepsydra; dropsy; hydra; hydrangea; hydrant; hydrargyrum; hydrate; hydraulic; hydro-; hydrogen; hydrophobia; hydrous; Hydrus; inundate; inundation; kirsch-wasser; nutria; otter; redound; redundant; surround; undine; undulant; undulate; undulation; vodka; wash; water (n.1); wet; whiskey; winter.

It is the hypothetical source of/evidence for its existence is provided by: Hittite watar, Sanskrit udrah, Greek hydor, Old Church Slavonic and Russian voda, Lithuanian vanduo, Old Prussian wundan, Gaelic uisge "water;" Latin unda "wave;" Old English wæter, Old High German wazzar, Gothic wato "water."