The word check has several common meanings:

1. To examine or verify something to make sure it's correct or safe. You might check your homework for mistakes before turning it in, or check that you packed your lunch before leaving for school. A pilot checks dozens of instruments before takeoff. When something needs careful attention, we double-check it: looking twice to be absolutely certain.
2. To stop or restrain something. A hockey player might check an opponent to slow them down. You might need to check your anger when your little brother breaks your LEGO creation. The phrase keep in check means to control something: “She kept her nervousness in check during the spelling bee.”
3. A written order to a bank to pay money from your account. When adults pay for things with a check, they write the amount and sign their name, and their bank transfers that money to whoever receives it. Checks were the main way people paid bills before electronic payments became common.
4. The pattern of squares you see on a checkerboard or certain fabrics. A tablecloth with a checkered pattern has alternating colored squares.
5. In chess, check means your opponent's king is under direct threat and must move to safety.