Security Label definition in Computer Security terms:
Definition(s): 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(s): CNSSI 4009-2015 (NIST SP 800-53 Rev. 4)
NIST SP 800-53 Rev. 4
Explicit or implicit marking of a data structure or output media associated with an information system representing the FIPS 199 security category, or distribution limitations or handling caveats of the information contained therein.
Source(s): NIST SP 800-18 Rev. 1
reference: CSRC Glossary