The phrase 'black box' refers to an electronic device that records and stores important data, often used in aviation or automotive industries. Some synonyms for 'black box' are flight recorder, data recorder, event data recorder (EDR), event recorder, and cockpit voice recorder (CVR). In the medical field, a black box can refer to a warning label on a medication with known serious side effects. Other synonym options for 'black box' include mystery device, indestructible recorder, and secret keeper. Whatever the industry or context, the key function of a black box is to record information that is critical for analyzing and improving performance.