While looking for some good pictures of roses for the current Días de los Muertos art project, I ran across this odd word - Quincunx. Odd and old, not to mention hard to pronounce and slightly naughty sounding.
Wikipedia has an entry for it. Merriam Webster has a definition. Visually it is the five spot on a domino - four dots on the corner and one in the middle. The origin is thus: "Latin quincunc-, quincunx, literally, five twelfths, from quinque five + uncia twelfth part". According to MW, first known use was 1485. Now I'm still thinking how does 5/12 relate to planting.