Security Associations definition in Computer Security terms:
Definition(s): Each instance of IPsec has a security association database (SAD) of IPsec connections, called security associations. SAs describe the endpoints of the secure connection, exact type of protection provided, cryptographic parameters and keys, expiration time, and label (Security Parameters Index or SPI) to identify packets protected with each SA.
Source(s): NIST SP 800-119
reference: CSRC Glossary