what ever the sourse of the word, catsup/ketchup has been an American condiment for a very long time.. colonial cookbooks have recipts.(recipes) for it, and the basics haven't changed.. it was originally chunkier, more like a chutney, made from tomatoes, spice, vinegar and sweetner.(molasses originaly) over time, it got smoother and sweeter.. until it is the homogonized sweet, mildy spicey, tomato basic condiment we know today.

remember the whaling industry was growing up pre-revolution, and american sailers were going round the world in search of whales.. NYC had the first customs house of US government, Sag Harbor, New Bedford, Nantucket, and all the other whaling towns of New England/Long Island followed fast behind.. Whaling ships brought in whale oil and other exotics from many foriegn ports and the new goverment was quick to impose duty tax! but there was no tax on ideas.. and condiments like ketchup came in free!

to my thinking tomato sause is mild, (maybe salt, and little basil) pureed tomatoes.. reduced slightly to thicken. it is the basis of other sauses.. red (pasta sause), cocktail sause for sea food, tomato soup, etc. i almost never use it as it comes from the can, but only use it as an ingredient in something else.