What is catsup?

What is catsup?

In a year plus time I will need to know, because I've just made some elderberry catsup. The recipe says "strain before using".

Am I straining out the elderberry-flavoured vinegar? Or straining out the onions and the spices?

An internet search has not been helpful - it seems to be a regional name for ketchup. There is no mention of processing it in my recipe, thereby combining the ingredients, which is just as well as I don't use a food processor because I hate the idea of having to wash one.