A *square* is a figure with four equal sides and four right angles. It's a popular shape for windows and record albums, among many other things.

*Square* has many different metaphorical uses. Old towns had square open areas for meetings, so now "town square" means meeting place, even if it's not shaped exactly like a square. If you settle your debts, you square them, and if someone calls you a square, they mean you're boring, rule-abiding, and lame. In math, a square is the product of something multiplied by itself. If you square your plans with someone, you line them up.