Security Label

The means used to associate a set of security attributes with a specific information object as part of the data structure for that object.
SOURCE: SP 800-53

A marking bound to a resource (which may be a data unit) that names or designates the security attributes of that resource.
SOURCE: FIPS 188

Information that represents or designates the value of one or more security relevant-attributes (e.g., classification) of a system resource.
SOURCE: CNSSI-4009