Where you live can determine whether you describe something that is diagonally across from something else as kitty-corner or catty-corner. See the map of responses to my Facebook survey.
You know how time seems to fly? Well more than three years ago I surveyed my Facebook fans about whether they say kitty-corner or catty-corner, and turning that data into a post has been on my list of things to do ever since. Finally, here it is!
All the words come from the original base word cater which means “four” and comes from the French word for four: quatre.
The Oxford English Dictionary lists cater-corner as the main word and calls kitty-corner and catty-corner variants, but these are also Americanisms and the OED has a British bent, so I’m not surprised to find in an Ngram search that kitty-corner and catty-corner are actually used far more often than cater-corner. (h/t to @EditorMark for the Ngram search.)
As you can see from the map of responses, people in the South, as far west as Texas and as far north as Pennsylvania and Nebraska, are much more likely to say catty-corner, whereas everyone else in the US and Canada is more likely to say kitty-corner.
Many Other Spellings
What surprised me most about this survey was how many words people reported using other than kitty-corner and catty-corner. In many cases, it seemed as if people may have only heard the saying and then guessed at the spelling:
The Dictionary of American Regional English has even more variants: kitty-cross, kitty-katty, kittering, and kitty-wampus, which means “askew” instead of “diagonally across” like all the others. My mom used to say kitty-wampus (which the OED spells as catawampous), and I was disappointed to see that the OED lists the origin as unknown.
The bottom line is that kitty-corner is considered dialect and informal and you can spell it pretty much any way you want, although it does always take a hyphen. If you work for a formal publication, check how it’s spelled in your organization’s style guide or recommended dictionary.