This glossary provides handy reference for definitions for common terms relevant to Circonus, with links to provide further information. This list will be updated and expand over time.

Links in the first column will direct you to a relevant section in the Circonus User Manual. Where applicable, additional links are provided in the description.

Term Description
Acknowledgement Represents a single acknowledgement of an alert. Each acknowledgement has a defined start and end point during which the alert is considered acknowledged.
Active This refers to a metric that is currently being collected.
Alert This refers to the notification that can optionally be sent to a user/group/program/etc., as the result of an Event.
Annotation This refers to manual identification of something in the timeline. For example, you might Annotate a server being down for maintenance. The same condition might have also cause an Event and possibly an Alert to occur.
Bert This is Circonus's notification and case management system.
Broker Circonus operates a worldwide system of nodes for configuring checks and gathering metrics. These nodes are known as Circonus Public Brokers and are available for use by any active Circonus accounts. Enterprise Brokers are software appliances that can be downloaded and installed in a customer's datacenter for running checks and gathering metrics privately.
Bundle This is a collection of checks that have the same configuration and target, but collect from different brokers. A bundle can have one check or many checks in it, and changing the bundle effects all the associated checks.
This acronym stands for Circonus Analytics Query Language. This query language allows users to formulate queries for graphing complex transformations of collected data and allows fine-tuning of previously hidden parameters. Additional information is available in the CAQL Tutorial.
Circonus assesses services and processes the telemetry it collects during that assessment. These assessments are called "Checks" within Circonus. There are many Types of Checks in Circonus.
A metric cluster is a cluster of metrics defined by a set of queries.
Enzo This is Circonus's web stream, a real-time UI data system.
Ernie This is Circonus's fault detection system, a real-time rules engine.
Event This refers to what occurs when a threshold is breached. This may or may not generate an Alert.
FQ This is Circonus's preferred message queue system. It is available on Github from Circonus Labs, along with further documentation.
This is one type of graphic representation of a data distribution. A typical histogram will take many values and place them into bins, representing those bins in a bar chart or pictogram. Click here to learn more.
Hooper This is the Circonus Installer.
A host device (or target) is simply any other system that you want Circonus to monitor, whatever kind of system it might be (server, network device, application, etc.).
Maintenance This refers to a scheduled maintenance window for an account, check bundle, rule set, or host. During maintenance windows, alerts are suppressed.
Metric When checks are run, they produce a variety of telemetry information. Each of these data streams is called a "metric." For example, round-trip latency, and all the values measured to produce that stream of data, is one metric. CPU Utilization is another.
Module This refers to the type of a check. The preferred term is Type. 
NAPP Noit APPliance, this broker appliance is the custom configuration shipped with Reconnoiter.
Graph overlays allow you to view data related to a graph over top of the graph itself. The link to the left covers overlays in general, but click here to learn more about Analytics Overlays.
The large-scale monitoring and trend analysis software that runs on a Circonus broker. Available on Github from Circonus Labs.
Ruleset Rulesets define a collection of rules to apply to a given metric, which generate alerts when violated. Each rule has a severity which links to a contact group or groups to be notified about the alert.
Snowth This is Circonus's data storage system, a distributed time-series storage and analytics system.
A category assigned to an object for filtering purposes.
See Host, which is the preferred term in Circonus. A Host is the "Target" of a Check.
This refers to a means to setup a mass number of checks quickly by applying check bundles from one host (the master host) to a set of other hosts.
This refers to the type of a Check, for example, a Ping Check or an HTTPTrap Check.
This refers to a collection of graphs that allows quick correlation across the graphs.