The state of being severe.
The degree of something undesirable; badness or seriousness.
The state or fact of being turbulent or agitated; tempestuousness, disturbance.
Disturbance in a gas or fluid, characterized by evidence of internal motion or unrest.
Specifically, a state of agitation or disturbance in the air which is disruptive to an aircraft.
An instance or type of such state or disturbance.