The term 'SQUARE PILLAR' can be broken down into two words, 'SQUARE' and 'PILLAR'. A SQUARE is a four-sided shape with equal sides and angles, while a PILLAR is a tall, cylindrical structure used to support a roof or other structure. The crossword solution for this term is 'PIER', which is a structure built out over water, usually supported by pillars. Piers are often used as docking points for boats, and can also be used for recreational activities such as fishing.