GOSA (The Geyser Observation and Study Association) Glossary  
Cone-Type Geyser:
A geyser whose eruption is jetted as a steady column of water and steam from a vent with little or no surface pool. It is not necessary that the vent be at the top of a cone formation. Old Faithful Geyser is a cone-type geyser.
Cyclic:
A geyser that has a series of eruption at relatively short intervals separated from the next series by a relatively long quiet period.
Disturbance:
When applied to Norris Geyser Basin, describes a basin wide or partial basin change in not only geyser and pool behavior but also water temperatures and chemistry. When a disturbance occurs, many dramatic changes can take place. Many previously quiet geysers and pools start erupting. Other pools become murky or change color. And many geysers erupt much more vigorously. Not all geysers are affected positively though. The possibility of a major Steamboat eruption seems to be quenched by the onset of a disturbance for instance. What causes the disturbance? Well, one theory holds that the disturbance is the manifestation of a second hot water reservoir interacting with the surface features. This theory is supported by the change in water chemistry. Disturbances were first noted occurring in the Fall and covering the entire basin but have since been recognized in other seasons and sometimes only affecting small portions of the basin at a time.
Dormant:
When a geyser is not active, it is dormant.
Duration:
The period of time from the start of an eruption to the end of that eruption.
 
Fountain-Type Geyser:
A geyser whose eruptions occur in a series of separate burst, usually through a pool of water over the vent. Grand Geyser is a fountain-type geyser.
Fumarole:
A steam vent. A fumarole is related to a hot spring but the temperature is so high and the water supply so limited that all water is emitted as steam and no pool is able to form.
 
Geyser Gazer:
A geyser aficionado.
 
Geyser Hill Wave:
A theory proposed by T. Scott Bryan that attempts tie together some of the activity seen on Geyser Hill. The geyser hill wave can be thought of as a wave of energy