NSEC stands for the Non-Secure Delegation Signer (DNS) Resource Record. Synonyms for NSEC include Non-Secure Signer (also referred to as NRRSIG), NSEC3, NSEC5, and NSEC6. These terms generally refer to different versions of DNSSEC, which is a security extension for the Domain Name System that aims to prevent DNS spoofing and other cyber threats. The use of NSEC or its variants can help to ensure the security and authenticity of DNS queries and responses, making it easier to detect and prevent malicious activities. As such, it is crucial for organizations to stay updated with the latest NSEC-related developments and terminology.