-onna is a presumed hydronymic suffix, perhaps
pre-Indo-European. Observed in many river names [in particular in France] , it is generally analyzed as meaning 'source, spring' or 'river'.
Gaulishword *"onno" was glosed as 'flumen' ('river') in the Vienne glossary. This doubtful word [following Delamarre, Xavier (2003). "Dictionnaire de la langue gauloise" (2nd ed.). Paris: Editions Errance. ISBN 2-87772-237-6] was probably due to a theorization of the suffix "-onna".
This suffix is observed in river names as:
* Aisne < "Axonna"
* Aronde < "Aronna",
* Saône < "Sauconna",
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