So, in munching on my fries at dinner this evening, I was pondering. I had ketchup to dip my fries in. But what’s the difference between ketchup and catsup? And it’s a seriously weird word either way, so where did it come from? I decided that I must know, and so I did a little research. (Only a little, mind you. I’m lazy.)
Ketchup and catsup are different spellings of the same thing. Ketchup has pretty much become the standard spelling, although obviously catsup still pops up once in a while. It’s a modern, American variation of a European version of an Asian sauce. There is some debate about which sauce, but generally accepted to be a sauce based on brined or pickled fish or shellfish, herbs and spices.
See, told you this was a weird word. For a slightly more detailed article about the history, see my friends over at Mental Floss: http://mentalfloss.com/article/29649/whats-difference-between-ketchup-and-catsup
Or this link at Diffen, where you can compare anything: http://www.diffen.com/difference/Catsup_vs_Ketchup