keep something/someone at bay
keep (someone or something) at bay
To keep someone or something at a distance or from reaching full potency, especially in order to prevent harm to oneself. During my college years, the only things I had to keep hunger at bay were beans, rice, and plain pasta. You have to start meeting your minimum monthly repayments if you want to keep your creditors at bay. These tree frogs have a powerful poison on their backs that helps keep predators at bay.
keep something/someone at bayor
hold something/someone at bay
COMMON If you keep something or someone at bay or hold them at bay, you stop them from attacking you or harming you. By salting the meat, bacteria were kept at bay, preserving the meat for future use. Tooth decay can be held at bay by fluoride toothpaste and good dentistry. A dozen American soldiers held the crowd at bay until the helicopter lifted off. Note: When a hunted animal is at bay, it is trapped by the hounds (= hunting dogs) and forced to turn and face them to defend itself. However, if the animal is successfully defending itself in this position, you can say that it is holding the hounds at bay. This second use seems the most likely origin of the expression.