I am from New Zealand and was talking with some American friends. This led to discussing the word “caddicorner” - or “opposide corner”, its correct spelling, pronounciation (some said “Katticorner”), usage and origin. This also led further on to the term “caddiwampas” - or “head over heels”, which is in the similar vein.
I, from New Zealand had never heard this term before, and so was curious to its origins.
It’s actually spelled “cater-corner” or “catty-corner”. It comes from the Latin word for “four”. When you go catty-corner, you are making a diagonal across a square (more or less).
The word is of more recent origin that I would have expected, dating from the middle of the 19th century. It is mostly in North American usage. The first element is from the adverb cater (from French quartre) that dates from the late 16th century and means (according to the Shorter Oxford Dictionary) diagonally. Variants are cattycorner and catercornered. Where I grew up (western New York) we always said kitty-corner.