@cassolotl @PierreM Ok that’s actually a little tricky. Fleuve goes to the sea/ocean, rivière goes to anything else (lake, other river). So a rivière CAN be also an affluent/tributary, but we won’t use that word to define it, only when it’s technically relevant (like « Rivière X est un affluent de fleuve Y »).

BUT we also will colloquially just call fleuve whatever is big/long and rivière the smaller ones, no matter where they end.