This is the formatted '<integer>,<description>' string that gives the human-readable label corresponding to the numeric value in cenAlarmSeverity. As with the status and category definition fields, this lets a receiving dashboard show a meaningful severity label without maintaining its own static mapping table, which matters since different Cisco management applications may use different severity scales under the hood. A severity value of 85 paired with a definition string of '85,Critical - Immediate Action Required' tells the operator exactly how to interpret that number without consulting external documentation.