Hydronyms from various languages can all share a common etymon.
From the en.wikipedia.org
Great question and I really like etymon and perguntador's entries.
From the economist.com
Papyrus is also the etymon of paper, a similar substance.
From the en.wikipedia.org
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A simple form inferred as the common basis from which related words in several languages can be derived by linguistic processes
A source word of a given word
(plural, etyma): An older word that is a source for a newer one. See etymology.
An earlier form of a word in the same language or an ancestor language. See also: Wanderwort.
Etymological source for a word. The American Heritage Dictionary shows the immediate etymon for words borrowed into English and then more distant etymons in the development of the word. The OED gives considerable etymological information.