1. To orient something along a particular line, edge, angle, or plane. A noun or pronoun can be used between "square" and "up." Make sure you square up the picture frame before you nail anything into the wall. You should try to square your shoulders up so that you aren't so hunched while you sit.

2. To orient one's body to be parallel to some line or plane. Make sure you square up to the tee before you swing the golf club. He squared up to the tree and started striking it with his axe.

3. To confront someone in defiance or hostility or in preparation for a fight. He squared up to the guy who had been making lewd remarks about his girlfriend. Protestors squared up to police during the march, but thankfully there was no violence.

4. To face someone in competition. The two boxers are squaring up tomorrow at 7 PM.

5. To pay the balance of what is owed to someone. You get our jackets while I go square up with the bartender. Brian and I need to square up for those plane tickets soon—I hate owing someone money.