Covert channel in which one process signals information to another process by modulating its own use of system resources (e.g., central processing unit time) in such a way that this manipulation affects the real response time observed by the second process.
NIST SP 800-53 Rev. 4 under Covert Timing Channel
A system feature that enables one system entity to signal information to another by modulating its own use of a system resource in such a way as to affect system response time observed by the second entity. See: covert channel.
(IETF RFC 4949 Ver 2)