System Management Mode (SMM) definition in Computer Security terms:
Definition(s): A high-privilege operating mode found in x86-compatible processors used for low-level system management functions. System Management Mode is only entered after the system generates a System Management Interrupt and only executes code from a segregated block of memory.
Source(s): NIST SP 800-147
NIST SP 800-147B
reference: CSRC Glossary