Kitty-corner, or catty-corner, is a classic example of the phenomenon known as folk-etymology. When a word or phrase makes little apparent sense, it will often mutate into a form that seems more familiar.
The term was originally catercorner. Cater is an old dialectical term for diagonal. It derives from the French quatre or four. Cater dates to the16th century, appearing in Barnaby Googe’s 1577 translation of Heresbach’s Foure Bookes of Husbandry:
The trees are set checkerwise and so catred [partim in quincuncem directis], as looke which way ye will, they lye level.
By the early 19th century, the folk etymology had set in. From Joseph C. Neal’s 1838 Charcoal Sketches:
One of that class...who, when compelled to share their bed with another, lie in that engrossing posture called “catty-cornered.”
(Source: Oxford English Dictionary, 2nd Edition)
Copyright 1997-2015, by David Wilton