keel

Keel comes from Middle English kele, from Old Norse kjǫlr, from Proto-Germanic *keluz, whose deeper origin is unknown. It pushed aside the native Old English word ċēol, which came from a related root.

The facts available don't describe a shift in meaning beyond this word replacing its Old English cousin ċēol — both pointed to the same part of a ship, but the Norse-derived form won out.

Keel is distantly related to the word kile, though the exact nature of that connection isn't detailed.