Trojan Horse definition in Computer Security terms:
Definition(s): A computer program that appears to have a useful function, but also has a hidden and potentially malicious function that evades security mechanisms, sometimes by exploiting legitimate authorizations of a system entity that invokes the program.
Source(s): CNSSI 4009-2015
NIST SP 800-82 Rev. 2 (RFC 4949 75)
A useful or seemingly useful program that contains hidden code of a malicious nature that executes when the program is invoked.
Source(s): NIST SP 800-28 Version 2
A computer program containing an apparent or actual useful function that also contains additional functions that permit the unauthorized collection, falsification, or destruction of data.
Source(s): NIST SP 800-47
reference: CSRC Glossary