foursquare vs rock solid

foursquare

• Solid, robust. 

• Pertaining to the International Church of the Foursquare Gospel. 

• Having four equal sides; square. 

• Pertaining to a four-square cipher. 

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

• A four-square cipher. 

rock solid

• Very strong and dependable. 

• Physically very solid; very difficult to move.