Agitation; the state of being perturbed
Variation in an orbit due to the influence of external bodies
A small change in a physical system, or more broadly any definable system (such as a biological or economic system)
Intense dread, fright, or fear.
The action or quality of causing dread; terribleness, especially such qualities in narrative fiction.
A night terror.
Terrorism.
Something or someone that causes such fear.