adjective
Having four equal sides; square.
(by extension) Solid, robust.
(cryptography) Pertaining to a four-square cipher.
Pertaining to the International Church of the Foursquare Gospel.
noun
(uncountable) Alternative form of four square.
(countable, cryptography) A four-square cipher.
(countable, architecture, US) A boxy style of domestic architecture with four rooms to a floor, one of which is usually a stair hall.