Code black: While there is no formal definition for a "Code," doctors often use the term as slang to refer to a patient in cardiopulmonary arrest , requiring a team of providers (sometimes called a "code team") to rush to the specific location and begin immediate resuscitative efforts.

The term "Code" derives from the practice at many institutions of using "Code" designations followed by colors ("Code blue"), numbers ("Code 10") or other qualifying terms to alert personnel in the event of an emergency and to specify what type of emergency is occurring. (Code pink is often used to alert security that a baby is missing from the hospital nursery!)

There are no standard definitions or conventions for the use of "Code" designations, and each institution that uses a "Code" system can decide how to apply the system. For example, while "Code blue" refers to a cardiopulmonary arrest at many hospitals, it doesn't necessarily mean the same thing everywhere. Other types of emergencies, (for example bomb threats, terrorist activity, child abductions, or mass casualties) may also be given "Code" designations.