A level, usually configurable, describing the type and/or quantity of output that an application writes to a log file. Set the logging verbosity of an application to specify how much and what kind of information the application writes to its log file. The Splunk Enterprise logging verbosity levels are DEBUG, INFO, NOTICE, WARN, ERROR, CRIT, ALERT, FATAL, and EMERG. These are in order of most to least verbose.
For more information
In the Troubleshooting Manual: