What is the meaning of Foursquare?

Having four equal sides; square.

Solid, robust.

Pertaining to a four-square cipher.

Pertaining to the International Church of the Foursquare Gospel.

Alternative form of four square

A four-square cipher.

A boxy style of domestic architecture with four rooms to a floor, one of which is usually a stair hall.

Source: wiktionary.org