1. To do that which fulfills one's own desires, expectations, or ambitions, especially when failing to consider those of anyone else. It really doesn't matter to me how you arrange the furniture in here, so just suit yourself! Look, Tom and his wife are always going to suit themselves, so don't tie up everything you want to do on this trip with them.

2. A set phrase used in the imperative indicating that the speaker accepts or is indifferent to the other person's decision or preference, especially when it runs contrary to their own desires or expectations. A: "I would just rather not go to a wedding where I won't know anyone." B: "Fine, suit yourself. I'll just go alone." A: "I don't think I'll come to dinner after all." B: "Suit yourself. Should be fun, though."