About [[Osm:Geocoder.search osm nominatim.prefix.waterway.connector/en]]
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Fragment of a discussion from Translating talk:OpenStreetMap/LiquidThreads
I'd rather guess that "a connection by a waterway" between two points is meant.
I have no idea what that's for I'm afraid - those messages are related to tags use for objects in the database, so that message would be a description for something tagged as waterway=connector but that tag combination is not even listed in our wiki.
About the best I can deduce from the english text is that it would be for a stretch of waterway that connected to other, larger, waterways.