Upright means standing straight up, vertical rather than leaning or lying down. A flagpole stands upright. When you sit with good posture, your spine is upright. An upright piano is taller than it is wide, with its strings running vertically instead of horizontally like a grand piano.

The word also describes someone who acts with honesty and integrity. An upright citizen follows the rules, treats others fairly, and does what is right even when no one is watching. When you return a wallet you found instead of keeping it, you're being upright. When you admit a mistake instead of blaming someone else, you're acting upright.

These meanings connect: just as something physically upright stands firm and steady, a person who is morally upright stands firm in their principles. They don't bend the truth or lean toward dishonesty. In older English, people would sometimes call an honest person “upstanding,” which captures the same idea of standing straight and true.