Definitionen
1.NounEllipsis of tomato ketchup (“a tomato-vinegar-based sauce, sometimes containing spices, onion or garlic, and (especially in the US) sweeteners”)."tomato ketchup; This diner serves ketchup in red bottles, and mustard in yellow ones."
2.NounSuch a sauce more generally (not necessarily based on tomatoes, but with mushrooms, fish, etc.). This is the older meaning.
3.VerbTo cover with ketchup.
4.Verb↑ "Ketchup", Oxford English Dictionary (online edition, 2020).
5.Verb↑ “Is There a Difference Between Ketchup and Catsup?”, Slate, Aisha Harris, April 22, 2013