foursquare

1. (by extension) Solid, robust.Examples: "Standing foursquare in the heart of the town, at the intersection of the two main streets, a "jog" at each street corner left around the market-house a little public square, which at this hour was well occupied by carts and wagons from the country and empty drays awaiting hire […]."; "It is surprising to find white wine of apparently low acidity keeping well at all. Yet at ten years (a good age for it today) it has a haunting combination of foursquare breadth and depth with some delicate, intriguing, lemony zest."; "Another initially foursquare wine that develops lovely fruit in the glass, with a toasty-biscuity finish beginning to build."broadly

2. (cryptography) Pertaining to a four-square cipher.