A setup is the way something is arranged or organized before it gets used. When you prepare a board game by laying out the pieces, shuffling the cards, and putting the money in the bank, you're doing the setup. When a band arrives early to arrange their instruments, connect the microphones, and test the sound system before a concert, that's their setup.

The word also describes the equipment or system itself once it's arranged. A scientist might have an elaborate laboratory setup with microscopes, computers, and special lighting. A gamer might be proud of their gaming setup with multiple monitors and a comfortable chair. You can also talk about someone's bedroom setup or desk setup, meaning how they've organized their space and what equipment they have.

In stories and jokes, a setup is the first part that prepares you for what comes next. The setup of a joke gives you the information you need to understand the punchline. If someone says, “A horse walks into a bar,” that's the setup, and you know something funny is coming.

When you set up something (two words, used as a verb), you're arranging it: “Let's set up the tent before it gets dark.” When you set someone up, you're either arranging something nice for them (like setting up a surprise party) or tricking them unfairly (like setting up someone to take the blame for something they didn't do).