The term "onBlur" refers to an event in web development that occurs when an element, such as an input field, loses focus. This can happen when a user clicks outside the element or navigates to another part of the page. Developers often use the onBlur event to trigger specific actions, such as validating user input or saving data. In JavaScript, the onBlur event can be handled using event listeners. For example, when a user finishes typing in a text box and clicks away, the onBlur event can execute a function to check if the input meets certain criteria. This enhances user experience by providing immediate feedback.