Learning about NY, what's a kill?, thanks for posting

Kill is the old dutch word for a (usually elongated) body of water, such as an inlet, a river, a fjord or a strait. The name is commonly found in NY place names, such as Catskill and Fishkill.
Since the Dutch inhabited the Hudson valley before the British, a lot of names still have dutch origins, like Kinderhook and Harlem.

thanks Tar3k for the info, one of the reasons I enjoy puzzgrid so much