Overwrite a memory location with data consisting entirely of bits with the value zero so that the data is destroyed and not recoverable. This is often contrasted with deletion methods that merely destroy reference to data within a file system rather than the data itself.
NIST SP 800-63-2 under Zeroize [Superseded]
NIST SP 800-63-3 under Zeroize
To remove or eliminate the key from a cryptographic equipment or fill device.
(NSA/CSS Manual Number 3-16 (COMSEC))