Catsup was once the predominant spelling of the tomato-based condiment, but most modern writers and editors prefer ketchup. The latter more closely approximates the word’s pronunciation, and it’s also closer in sound to the likely source—either the Cantonese k’e chap or the Malay kechap, both originally types of fish sauce. Catchup is listed in dictionaries, but few writers use it.
Examples
Ketchup outnumbers catsup on the web by approximately 16 to 1—and most major publications use the more popular spelling. For example, these publications prefer ketchup:
Adding mayonnaise—or, heaven forbid, ketchup—turns it into something else entirely. [Brownsville Herald]
Ketchup used to be the condiment of choice for Americans. [NPR]
The stand, where ketchup on franks is a no-no, has won more fans since the results were announced last week … [Chicago Sun-Times]
How many bottles of squeezy ketchup do you get through per episode? [The Guardian]
But catsup is not completely absent—for example:
Houston wore its alternate McRockets uniforms with the catsup-and-mustard color scheme. [USA Today]
There was a charm to the smoked catsup on the side, though … [Coast Weekend]
