European IE languages (minus those from Balkans) shared a common word *mori-, whose meaning 'stagnant water, lake, sea' provided word for 'sea'. If European IE settlers had a name for 'sea', what sea are they refering to? Most plausible is Black Sea, but Baltic and Adriatic are possibilities. If the name means "lake", what lake is that? How could Celts keep a word for 'sea' moving across Europe? Should we infer that while Proto-Celts are arriving at France, did they keep contact to marine communities?
JS Lopes